Hidden Homelessness: A Scoping Review and Avenues for Further Inquiry

Abstract

Traditional interpretations of homelessness focus on people living on the streets or in shelters. However, homelessness encompasses many more living situations. This article reports on a scoping review of studies on hidden homelessness. A systematic search in scientific databanks was combined with an exploration of Google Scholar. The results of the review reveal a lack of consensus regarding the definition of the concept. Moreover, since most studies focus on a certain subgroup in the population, it is hard to compare profile characteristics of people living in different forms of homelessness. The applied research methods prove to be valuable, although they often underestimate the number and/or character of the phenomena. Very little longitudinal research on hidden homelessness seems to be available. Based on the findings of the scoping review, the article draws up an agenda for further research in order to capture the complex reality of contemporary forms of homelessness.

Introduction

Homelessness is an active research topic across many disciplines, including political sciences, social work, sociology, psychology and health sciences (see, for instance, Phillipot et al., 2007; Fazel et al., 2014; Parsell and Clarke, 2019). While there is considerable research on the subject, in daily interactions, in the media as well as in public policy, people who are homeless are often framed simplistically: in particular, as highly dysfunctional – ‘drunk, stoned, crazy and sick’ (Snow et al., 1994: 462; Lister, 2004; McNaughton-Nicholls, 2009; O’Carroll et al., 2017; Vázquez et al., 2017; Weng and Clark, 2017; Parsell, 2018). Accordingly, their homelessness is often attributed to an incapacity and failure to function in what are presented as unproblematic social systems (Parsell, 2018). Moreover, in the everyday ‘common-sense’ view held by the general public, as well as in some official definitions, homelessness is frequently interpreted as ‘sleeping rough’ or ‘houselessness’, narrowing the focus to those living on the streets or in homeless shelters (Widdowfield, 1999; Busch-Geertsema et al., 2014; Zufferey, 2017; Parsell, 2018).

However, in the research literature on homelessness, broader conceptions have been proposed (Minnery and Greenhalgh, 2007; MacKenzie, 2012). An example of such a broader approach is the European Typology of Homelessness and Housing Exclusion (ETHOS), launched by the European Federation of National Organisations Working with the Homeless (FEANTSA) (Amore et al., 2011). Notwithstanding the analytical challenges of such a broad conception of homelessness (Marpsat, 2005; Amore et al., 2011), one of the achievements of ETHOS is that it covers a number of living situations which amount to forms of homelessness and housing exclusion across Europe: rooflessness (without a shelter of any kind, sleeping rough), houselessness (temporarily staying in an institution or shelter), living in insecure housing (threatened with severe exclusion due to insecure tenancies, eviction, domestic violence) and living in inadequate housing (in caravans on illegal campsites, in unfit housing, in extreme overcrowding). ETHOS thereby draws attention to people who experience forms of housing exclusion that remain largely invisible in research, public policy and homeless services (notably the insecure and inadequately housed, but also forms of houselessness). People in such situations are sometimes referred to as ‘hidden homeless’.

The term ‘hidden homeless’ is not only used by scholars but also by campaigning organisations, public authorities and policy makers. From a campaigning perspective, ’hidden homelessness’ might be a well-chosen term to focus attention on people whose housing difficulties are often not widely recognised. Organisations in the UK such as Shelter and Crisis (Reeve and Batty, 2011) apply the term to homeless singles who mostly rely on their own survival strategies and therefore stay hidden from services. The organisations argue this leads to unnecessary long periods of homelessness. An Australian-based NGO refers to ‘hidden homeless’ when addressing the housing problems of a considerable group of asylum seekers who live in the community while their applications are processed (Liddy et al., 2010). They are often in a vulnerable position, which makes them move in and out of homelessness while there is no follow-up by public authorities. In Belgium, the Centre for General Welfare (CAW) referred to hidden homelessness in a campaign on young sofa surfers hiding from society to avoid the homeless label (CAW, 2020). Public authorities use the term as well: for example, the Welsh Government in a campaign focused on young people, based on the concern that young people often remain unaware that their temporarily living situation is considered as homelessness. Therefore they only contact social work organisations relatively late (Welsh Government, 2020).

Despite the growing use of the term ‘hidden homelessness’, there is no shared definition and the term is inconsistently applied (Reeve and Batty, 2011). One of the reasons hidden homelessness lacks conceptual clarity is because its use has often been rhetorical, serving to draw attention to an issue, rather than conceptual. The absence of an objective definition poses methodological challenges to research on hidden homelessness, as does the invisible character of the phenomenon. People who have been classified as hidden homeless might not regard themselves as such (Pleace and Bretherton, 2013). Moreover, as hidden homeless people could be wary of official agencies, non-response and refusal might be especially high, making it difficult to measure the size of the group and to conduct longitudinal research (Nicaise and Schockaert, 2014).

This article reports the results of a scoping review on the available empirical studies about hidden homelessness. A scoping review is a process of summarising a range of evidence in order to convey the breadth and depth of a field. In line with the purposes of a scoping review, the aims of this scoping review are to give a clear indication of the volume of empirical studies available about hidden homelessness, to examine the operationalisation of the concept, to describe which methods have been used and to identify profile characteristics and the trajectories of people designated as hidden homeless (Munn et al., 2018: 2). The analysis leads to conclusions about the usefulness of hidden homelessness as a guiding concept and provides a basis for identifying and analysing knowledge and research gaps in homelessness research.

Methodology

Our scoping review is based on the five-stage approach developed by Arksey and O’Malley (2005), taking into account later applications and adjustments (Levac et al., 2010; Daudt et al., 2013; O’Flaherty and Phillips, 2015; Pham et al., 2014). The five stages are: (1) Identifying the initial research questions, (2) Identifying relevant studies, (3) Study selection, (4) Data charting and collation, and (5) Summarising and reporting findings.

Identifying the initial research questions

The review was guided by four research questions, based on the aims we identified in the introduction:

1. 1. How is hidden homelessness defined in the literature?

2. 2. Which methods are applied in studying hidden homelessness?

3. 3. What are the described profile characteristics of hidden homeless people?

4. 4. If longitudinal studies are available: What do we know about the trajectories of people designated as hidden homeless?

Identifying relevant studies

In order to find relevant studies on hidden homelessness, three electronic databases to identify peer-reviewed literature were selected: Sociological Abstracts (ProQuest), Scopus and Web of Science. While the first two databases concentrate on social sciences, Web of Science covers all scientific disciplines. In addition, Google Scholar was used to search for grey literature. To ensure a broad coverage of available literature, we opted for a general key term and scanned the databases for ‘hidden homeless*’. This systematic search was guided by inclusion and exclusion criteria to guarantee the relevance of the literature. In order to capture recent research, the selected studies were published from 2010 onwards. Other grounds for exclusion were language, student dissertations, book reviews, editorials and personal opinions, and articles lacking the term ‘hidden homeless(ness)’ or an in-depth discussion of its conceptualisation.

Study selection

The initial search in the three electronic databases was performed on December 23, 2019. This resulted in eleven hits in Sociological Abstracts (ProQuest), thirty-four hits in Scopus and sixteen hits in Web of Science. The search in Google Scholar was performed on January 30, 2020, with a custom range of items since 2010. Again ‘hidden homeless*’ was the keyword. As suggested by Pham et al. (2014: 373), the a priori decision was made to screen only the first 100 hits (as sorted by relevance), as further screening was unlikely to return more relevant articles (Stevinson and Lawlor, 2004).

In total, thirty-two duplicates were identified, leading to 129 unique records. A first screening of these records led to the exclusion of fifty records, based on the exclusion criteria of language and item type, leaving seventy-nine records for screening. In a following phase, the full text versions of these seventy-nine records were screened by the authors. Further guided by the inclusion and exclusion criteria, another fifty-seven records were excluded from the review because they were not based on empirical research or lacked an in-depth discussion of the topic.

The process of article selection was informed by the Preferred Reporting of Items for Systematic Reviews and Meta-Analyses (PRISMA) statement (Moher et al., 2009). Figure 1 illustrates the selection process in the PRISMA flowchart as adapted by Pham and colleagues (2014). The selection process resulted in the exclusion of 107 of the 129 identified items from the scoping review. Thus, the number of selected records for the data charting and collation was twenty-two. Nine studies were conducted in Canada, six in the UK, three in the USA, two in Ireland, one in Greece and one in Belgium.

Figure 1. PRISMA flowchart of study selection process.

Data charting, collation, summarising and reporting

In the next step, general information about the study and specific information related to the study question were summarised (Daudt et al., 2013). The summaries included the full reference, key words, the location where the research took place, the aims and outcomes and information concerning the four research questions. The summarising process was conducted by one researcher and reviewed by the two other authors. In the last step, the findings were analysed and reported, as presented in the next sections of this article.

Defining hidden homelessness

As shown in Table 1, the number of definitions of hidden homelessness in the literature is remarkable. Each item in the scoping review applies a different definition. While some of these descriptions are very broad and include an extensive range of phenomena, others refer to a specific situation such as sofa surfing with friends, family or others.

Table 1 Interpretations of hidden homelessness per item and origin

Sofa surfing and hidden homelessness

Sofa surfing, or couch surfing, is often used as a synonym for hidden homelessness (Minich et al., 2011; Peters, 2012; Crawley et al., 2013; Findlay et al., 2013; Mayock and Corr, 2013; Elwell-Sutton et al., 2017; Mayock and Parker, 2019) while other authors consider it a component of hidden homelessness (Sorensen, 2010; Clarke, 2016; Rodrigue, 2016; Elwell-Sutton et al., 2017; Kauppi et al., 2017; Demaerschalk et al., 2019).

Sofa surfing is again subject to different interpretations, although all definitions contain similar elements. A fairly comprehensive definition is offered by the Canadian Observatory on Homelessness (Crawley et al., 2013; Rodrigue, 2016):

(…) people who stay with friends, family, or even strangers. They are typically not paying rent, their duration of stay is unsustainable in the long term, and they do not have the means to secure their own permanent housing in the future. They differ from those who are staying with friends or family out of choice in anticipation of prearranged accommodation, whether in their current hometown or an altogether new community. This living situation is understood by both parties to be temporary, and the assumption is that it will not become permanent (Gaetz et al., 2012: 4).

All definitions of sofa surfing in the scoping review mention friends or the (extended) family as hosts, and some add acquaintances or strangers (Mayock and Parker, 2019). The lack of choice is often stressed and is closely connected to a lack of means to secure stable housing. Clarke (2016: 60), for example, describes sofa surfers as individuals staying with friends or family, ‘as they have nowhere else to go’. Sofa surfing is considered as such only as long as it concerns a temporary arrangement.

Some other terms have been used as a (close) synonym for sofa surfing. Several authors mention that the hidden homeless are also referred to as ‘concealed homeless’ or being ‘doubled up’ (Crawley et al., 2013; Mayock and Parker, 2019). Others consider ‘doubling up’ as a distinct form of hidden homelessness (Kauppi et al., 2017). A possible explanation is that in situations of ‘doubling up’ there is no clear host-guest relation, but rather two or more parties sharing accommodation.

The role of legal regulations

Legal regulations may influence what is considered to be hidden homelessness. In the scoping review we noticed how interpretations of the concept of hidden homelessness in England-based publications take the person’s or household’s legal status into account. These authors usually refer to the non-statutory homeless group when framing hidden homelessness (Bennett, 2011; Reeve and Batty, 2011; Clarke, 2016; Elwell-Sutton et al., 2017). Up to 2017 in England, statutory homeless people were those who contacted a local authority, met the criteria of being unintentionally homeless and were considered to be in priority need. Being statutorily homeless entitled them to housing offered by the local authority (Elwell-Sutton et al., 2017). In a broad sense, hidden homelessness includes sofa surfers, rough sleepers, squatters and those living in severely overcrowded conditions (Reeve and Batty, 2011). More often, hidden homelessness is described as a component of the non-statutory homeless group (Bennett, 2011; Clarke, 2016; Elwell-Sutton et al., 2017). For example, Elwell-Sutton et al. (2017: 27) divided their research subjects (all non-statutory homeless people) into three categories: (1) ‘single homeless in accommodation’, including those in hostels and night shelters; (2) ‘rough sleepers’; and (3) the ‘hidden homeless’, including sofa surfers and squatters.

ETHOS and ETHOS Light

Some researchers make use of the ETHOS and ETHOS light typology to explain hidden homelessness, although in different ways. Anthopoulou et al. (2019) focus on ETHOS’s conceptual categories of people living in insecure and inadequate housing, whereas Mayock and Parker (2019: 469) refer to the ETHOS living situation of ‘Temporarily staying with family/friends’. Demaerschalk et al. (2019: 106) make use of the ETHOS Light typology to define and investigate hidden homelessness, using ‘hidden homeless’ to refer to people who are provisionally accommodated: (1) living in non-conventional dwellings (ETHOS Light category 5), such as mobile homes, a squat, a garage or (2) homeless people living temporarily with family and friends (ETHOS Light category 6). In both cases, people are provisionally accommodated due to a lack of housing, lacking the privacy of an own home and the legal rights to occupancy.

Not making use of homelessness services, absent in homeless counts

Some studies define hidden homeless as those not (regularly) making use of homelessness services (Sorensen, 2010; Clarke, 2016; Metraux et al., 2016; Mayock and Parker, 2019). They do not use shelter and homeless outreach services (Metraux et al., 2016), possibly because they have had negative experiences with the service system (Mayock and Parker, 2019) or because they are unaware of the available services or do not wish to make use of them (Clarke, 2016: 60). As classical Point-in-Time (PIT) counts focus on rough sleepers and those who are in contact with official and established services for the homeless, homeless people who are not visible in the streets and who do not use homeless services are not covered by this methodology (Rose and Davies, 2014; Clarke, 2016; Metraux et al., 2016).

Other dimensions of hidden homelessness

Some of the reviewed items explore or at least touch upon other dimensions of hidden homelessness. Thus, one article describes young women with children, having a roof over their head but feeling ‘homeless at home’ for diverse reasons: for example, because they feel condemned to a low-quality housing system (Bennett, 2011). A second dimension pertains to the rural context, where homelessness tends to remain more hidden (Bennett, 2011; Kauppi et al., 2017; Anthopoulou et al., 2019). Kauppi and colleagues (2017: 69) describe seven types of hidden homelessness in rural and northern places in Canada, namely people living: (1) in tents or recreational vehicles, (2) in substandard housing, (3) in housing that is actually not affordable, (4) through couch surfing, (5) doubling up/overcrowding, (6) survival sex or (7) staying in motels or single rooms. In addition, they mention that challenges due to the lack of affordable housing are strongly connected to hidden homelessness.

Methods used in the reviewed studies

Since hidden homelessness refers to a broad range of phenomena, there is also a variation in the applied methods. Table 2 gives an overview of the records per type of research method: eleven quantitative, nine qualitative and two mixed method studies.

Table 2 Applied research methods

Asking questions during a PIT count

A PIT count is a snapshot of the number of homeless people at a given moment (Sorensen, 2010). PIT counts are often combined with short survey questions to identify homeless people (Findlay et al., 2013). There have been several attempts to improve PIT counts by including strategies to identify hidden forms of homelessness. Our scoping review found two studies discussing such attempts. First, The 2010 Edmonton Homeless Count sought to include people in hidden homelessness by not only approaching people in homeless services, but also at places where homeless people who tend to not use homelessness-related services could be present, such as a bottle depot (Sorensen, 2010: 3). They asked them the question: ‘Do you have a permanent residence to return to tonight?’. And second, The Saskatoon Homeless Population 2012 Report reports the prompt screening question: ‘If you couldn’t stay there [friend’s house] tonight, would you sleep outside or in a shelter?’ (Findlay et al., 2013).

Quantitative survey analysis

Other authors describe strategies to estimate the amount of homeless people not included in a PIT count. Agans and his colleagues (2014) explain how they made a random selection of telephone numbers in order to ask respondents on the phone if anyone was living with them or staying on their property ‘because they do not have a regular or adequate place to stay due to a lack of money or other means of support’ (Agans et al., 2014: 219). Rodrigue’s report Hidden Homelessness in Canada uses the data from the 2014 General Social Survey on Canadians’ Safety, which consisted of a survey by telephone and cell phone with a sample size of 33,127 people. Eight per cent of the respondents answered positive to ‘have you ever had to temporarily live with family or friends, in your car or anywhere else ¹ because you had nowhere else to live?’ (Rodrigue, 2016: 10).

Clarke (2016) reports on an online survey with a representative sample of 2,011 young people (aged sixteen to twenty-five) in the UK. They were asked whether they had ever sofa surfed, which was defined as a situation ‘where individuals stay with friends or members of their extended family on their floor or sofa as they have nowhere else to go’ – and if they had, whether they had done so in the last year, and the length of time they had spent sofa surfing (Clarke, 2016: 63).

Qualitative research methods

Nine of the studies used a qualitative approach. Most of them opted for semi-structured interviews (Ogden and Avades, 2011; Reeve and Batty, 2011; Peters, 2012; Rose and Davies, 2014; Watson et al., 2016; Anthopoulou et al., 2019). For the study of trajectories of people in hidden homelessness, the exploration of pathways proves to be useful. Anthopoulou et al. (2019) and Mayock and colleagues (Mayock and Corr, 2013; Mayock and Parker, 2019) have applied such an approach by collecting biographical and in-depth interviews with special attention for critical moments in the lives of their respondents. Mayock and colleagues (Mayock and Corr, 2013; Mayock and Parker, 2019) re-interviewed the same people over two years.

Mixed methods

Some of the analyses are based on a combination of qualitative and quantitative methods. Kauppi et al. (2017) analysed the Canadian Social Survey and enriched this data with qualitative information: for example, from interviews of people with lived experience of homelessness. Rather than directly asking social workers whether their clients were homeless, Demaerschalk et al. (2019) asked them to describe their clients’ housing situation as a means to capture the broad spectrum of homelessness and housing deprivation that goes beyond rough sleeping and shelter use. The described housing situation was then coupled to ETHOS Light in order to count the amount of homeless people in a given social organisation.

Recruitment of participants

Although some authors apply different methods to reach out to the hidden homeless, in both qualitative and quantitative studies, researchers often turn to services to get in contact with what they consider as hidden homeless people (Ogden and Avades, 2011; Peters, 2012; Crawley et al., 2013; Mayock and Corr, 2013; Rose and Davies, 2014; Watson et al., 2016; Elwell-Sutton et al., 2017; Demaerschalk et al., 2018; Mayock and Parker, 2019). Also service providers themselves are often included in the research (Mayock and Corr, 2013; Kauppi et al., 2017; Demaerschalk et al., 2019).

Profile characteristics of the hidden homeless

Data on profile characteristics of hidden homeless persons should be interpreted with caution. First, the concept of ‘hidden homelessness’ is interpreted in many different ways, as we demonstrated earlier in this article (see Table 1). Naturally, the applied definition influences the highlighted profile characteristics. Second, the studies included in this scoping review usually focus on specific subgroups in society rather than on the general population, as listed in Table 3. Third, the majority of publications do not contain conclusions on profile characteristics of the researched subgroup.

Table 3 Researched subgroups

The majority of reviewed studies originate from a concern over a specific group, as is shown in Table 3. They start from the assumption that the researched subgroup might (disproportionally) experience hidden homelessness. Some of these items reveal profiles inside their target group that seem to be especially sensitive for hidden forms of homelessness (Clarke, 2016; Metraux et al., 2016; Rodrigue, 2016). Clarke’s and Rodrigue’s articles outline the most information on profile characteristics. Their operationalisation of hidden homelessness is explained in the chapter on quantitative survey analysis.

Not surprisingly, different studies report how (hidden) homelessness is more likely experienced by those with a history of social vulnerability and exclusion (Mayock and Corr, 2013; Clarke, 2016; Rodrigue, 2016; Mayock and Parker, 2019). For example, lower-skilled people and victims of childhood mistreatment are more likely to experience hidden homelessness (Rodrigue, 2016: 2). Clarke (2016) mentions ever having been in care or ever being assisted by a social worker as the most important correlation with sofa surfing. In Canada those who reported an Aboriginal identity are twice as likely (18 per cent) to have experienced sofa surfing or living in their car as to their non-Aboriginal counterparts (8 per cent) (Rodrigue, 2016). Also disability and illness seem, in some cases, to correlate with hidden homelessness (Rodrigue, 2016). Furthermore, Rodrigue (2016: 9) argues that Canadians who identify in categories other than heterosexual are more likely to have experienced hidden homelessness. The latter corresponds with findings on shelters and services not addressing the needs of LGBTQI+ people (Kauppi et al., 2017: 115). With regard to gender, the findings of this scoping review suggest a more or less equal share of hidden homeless women and men; albeit with a slight overrepresentation of men (Clarke, 2016; Rodrigue, 2016).

Concerning the issue of migration, Rodrigue (2016) reports that immigrants in Canada are less likely to be hidden homeless than Canadian born. Haan (2011) explains that migrants in Canada live in larger households compared to the Canadian born, but concludes that this does not necessarily reflect higher numbers of hidden homelessness. The latter is defined by Haan (2011: 44) as people who are homeless but avoid the shelter system or the streets by relying on their social support networks. However, Clarke (2016) states that non-British citizens in the UK are more likely to report having sofa surfed and more likely to have done so for a longer time.

It is not always clear whether profile characteristics of people in hidden homelessness differ from the general homeless population (Kauppi et al., 2017). Only a minority of records point at differences in profile characteristics between people in different forms of homelessness. Metraux et al. (2016) suggest that black, older and more disabled members of the homeless population in Philadelphia are more likely to seek out (homelessness) services than others (Metraux et al., 2016: 1338). By consequence white, younger people and people without disability might rather stay hidden for services.

Another possible difference, suggested in some studies, is that sofa surfers may have more access to social support networks, compared with people in other forms of homelessness, like rough sleepers who more often lack social support (Peters, 2012; Clarke, 2016).

Trajectories

In this review longitudinal information on the trajectories of people with experiences of hidden homelessness is scarce. An exception is the work of Mayock and colleagues, who have conducted longitudinal research on homeless youngsters in Ireland by following them over several years (Mayock and Corr, 2013; Mayock and Parker, 2019). Compared with other studies – which have demonstrated relatively high levels of success in young people exiting homelessness – a majority of respondents in their study appear to remain homeless over the three years of research. This does not mean that their living situations do not change. On the contrary: they move between housing and/or different homeless categories. The extent to which the young people of the sample entered into living temporarily with family members, friends and acquaintances or in a partner’s family home is called striking by the authors (Mayock and Parker, 2019: 469). Often this is an attempt to escape homeless services and a life in the margins. Sofa surfing appears to follow the stay in a reception facility, rather than preceding it. This study illustrates that sofa surfing is often alternated with episodes of sleeping rough (Peters, 2012; Mayock and Corr, 2013; Rose and Davies, 2014; Kauppi et al., 2017). Paradoxical to the latter, research on a general population (i.e. not focusing solely on the homeless population) shows how forms of sofa surfing may be temporary solutions for people who succeed in avoiding homelessness for a longer time. One of Clarke’s (2016) conclusions is that one third of young people experienced sofa surfing at some point in their life and one in five during the last year. Rodrigue (2016: 10) concludes that nearly one in ten Canadians have experienced hidden homelessness, but 27 per cent did so for less than one month.

Clarke (2016) suggests that sofa surfing is not necessarily a negative experience when it concerns a short-term arrangement, while sleeping rough must always be seen as a crisis situation. Several other authors, though, refer to safety risks, negative health impacts and other problematic consequences of even short periods of hidden homelessness (Minich et al., 2011; Reeve and Batty, 2011; Peters, 2012; Watson et al., 2016; Demaerschalk et al., 2019). Based on their qualitative research with professionals and homeless people, Demaerschalk et al. (2019: 113) state that ‘even though a lot of informal solidarity can be found, staying temporarily with family/friends and living in non-conventional housing is not that rosy’. The instability, lacking a home, the examples of abuse of trust, the negative effect on social relationships and the general vulnerability and dependence often prove to be a serious burden. Peters (2012: 334) concludes that sofa surfing is often stressful and demanding, since it may include having to vacate the accommodation during the day, providing services to the host, frequent moves, inadequate diets, and so on. Survival strategies to secure sleeping place in the short term may hinder efforts to escape homelessness in the longer term.

Towards a research agenda

This scoping review leads to four conclusions. First, there is no consensus concerning the definition of hidden homelessness. ‘Hidden homelessness’ is a widely used term by scholars, campaigning organisations and policy makers, yet despite its widespread adoption there has been insufficient critical reflection on its use and definition. The notion is used to designate very different situations, such as failing to fulfil the legal definition of homelessness, not being counted in measurement strategies, not making use of services for the homeless, feeling homeless at home, and living under inadequate or insecure housing conditions: for example, sofa surfing.

Second, hidden homelessness is studied by means of a wide variety of research methods. All the methods we encountered in the scoping review prove to be valuable, since they highlight different aspects of hidden homelessness. At the same time, most studies still underestimate the number and/or nature of hidden homelessness. As stated by Metraux and colleagues (2016: 1334), conventional enumeration and survey approaches run the risk of minimising and misinforming measures to address homelessness. Moreover, respondents hosting or being hosted by someone may be reluctant to admit it, since this might influence their entitlement to social housing or social benefits (Minich et al., 2011: 528).

Third, on the basis of the available studies, we are not able to clearly compile the profile characteristics of hidden homeless persons. Identified profile characteristics depend on the used definition of hidden homelessness. Besides, most studies rely on services for the homeless to detect hidden homeless persons. However, as it is unclear to what extent the target group makes use of those services, this methodological design runs the risk of producing biased results. Moreover, the vast majority of the studies start with a certain demarcation of the population based on age, gender, income situation or ethnic identity, resulting in a somewhat distorted view on the profile characteristics of homeless people.

Fourth, this scoping review yields little evidence on the trajectories of people in hidden homelessness and on the relation between hidden and more visible forms of homelessness. The work by Mayock and colleagues (Mayock and Corr, 2013; Mayock and Parker, 2019) suggests that young homeless people combine different types of homelessness over the years.

A limitation of this scoping review is that we did not conduct specific literature searches on certain forms of homelessness that may be considered hidden but are not literally referred to as such: for instance, sofa surfing, living in unconventional dwellings, squatting or living under the threat of domestic violence. That said, the study gives a clear overview of the use of hidden homelessness in the literature between 2010 and 2019.

Based on our analysis, we identify four possible research lines to further develop our understanding of homelessness. First, given the conceptual fuzziness, the term hidden homelessness should be made redundant in homelessness research (Pleace and Hermans, 2020). Although the notion may serve well as campaign rhetoric, the scientific meaning of the concept seems to be blurry. Given the meaning of hiddenness differs fundamentally between the reviewed studies, conceptual clarity, which is a precondition for the development of any specific research field, seems no longer feasible. Moreover, there is a (perhaps implicit) suggestion that hidden homelessness might be a less serious form of homelessness: this goes against the experiences of many homeless people (Bennett, 2011; Minich et al., 2011; Peters, 2012; Crawley et al., 2013; Mayock and Corr, 2013; Lee et al., 2016; Watson et al., 2016; Kauppi et al., 2017; Mayock and Parker, 2019; Preece et al., 2020). The development of a conceptual framework might instead focus on sofa surfing, since this concept is more delineated and refers to a more specific situation.

At the same time, at least three aspects of sofa surfing, ‘staying temporarily’, ‘staying somewhere because of a lack of other options’ and ‘staying with friends, family or strangers’, remain rather blurred; for who determines what is meant by a temporary stay, when does a choice become a necessity and may the relationship and the arrangements between hosts and guests not strongly differ? This review suggests that, rather than being guests, sofa surfers may become a source of income, a nonpaid housekeeper and/or a free babysitter (Peters, 2012; Demaerschalk et al., 2018). More research is needed into the process of sofa surfing, that focuses on objective aspects, such as the payment of rent and other conditions for residence, as well as the lived experiences, such as the affective relationship between the host and the visitor and the power dynamics that affect them. Rather than developing an additional framework, we suggest to incorporate these objective and subjective aspects in the operationalisation of ETHOS (living situation 8.1) and ETHOS light (category 6).

Second, building on the work by Mostowska and Dębska (2020) and Zufferey (2017), we argue for the adoption of an intersectional approach to researching homelessness. There is plenty of academic literature that links homelessness to power issues (for example: Neale, 1997; Lancione, 2016; Watts et al., 2018), but social processes and social identity categorisations related to race, gender, ethnicity, age, class, sexuality, ability, indigeneity, sedentariness, religion and other markers of identity are still somewhat underexposed in empirical research. Using the intersectional lens has the potential to overcome some of the shortcomings of the current work on homelessness (Zufferey, 2017), such as gender-blindness (Mostowska and Sheridan, 2016), ageism, ableism (Patterson et al., 2012) and the underestimation of migration as a structural cause (Hermans et al., 2020). The latter, and more specifically the mishmash of residence permits that determine social rights, leads to different forms of homelessness and to various survival strategies, including remaining hidden (Bloch, 2014).

Third, we call for methodological innovations such as longitudinal research and/or participatory action research in the field of hidden homelessness. On the one hand, longitudinal approaches can answer questions regarding to what extent the group of people reached by homeless services differs from people applying other strategies, such as sofa surfing. It can also provide more insight into the trajectories and pathways of (hidden) homelessness (Clapham, 2002, 2003). On the other hand, participatory action research assures a dialogue and collaboration with people living in (or at risk of) hidden homelessness or who have experienced hidden homelessness in the past, based on the principle that those affected should be engaged in the process of investigation (Lancione, 2016; Van Acker et al., 2021). Moreover, participatory action research aims to produce practical tools for dealing with the challenges experienced by people in their professional, community or private lives. To capture nuance and complexity, there is an ongoing need for participatory action research as well as longitudinal research on hidden homelessness, in order to focus on the lived experiences of homelessness.

Fourth, whereas in migration research, informal actors are considered a crucial part of the arrival infrastructure and often form the subject of research (Elander et al., 2012; Osanami Törngren et al., 2018; Schrooten and Meeus, 2020), their role in the support of homeless people remains underexplored. Research on sofa surfing mainly focuses on staying with family or friends, and much less on staying with non-recognised and grassroots providers. Nevertheless, there are reasons to believe that persons in a precarious housing situation turn to such structures for shelter or support. For instance, the 2018 city count in Brussels, the capital of Belgium, demonstrated that over 30 per cent of the 4,187 counted individuals stayed with informal actors, such as religious organisations, squats or citizens (Quittelier and Horvat, 2019; Swyngedauw, 2019). Informal sheltering thus might play an important role in keeping people off the streets and keeping down the number of people who rely on public shelters. A better understanding of these arrangements may be an important link in preventing homelessness.