The chapter introduces readers to the major theories of the sector. Those covered include: market-failure theory, government-failure theory, contract-failure theory, voluntary-failure theory, supply-side (or entrepreneurship) theory, social-origins theory, interdependence theory, the commons, mediating structures, and associationalism.

To what extent are contemporary scholars using the ten explanations of the nonprofit sector described in Chapter 2? The authors use scholarship, or published academic articles, as data to answer this question. They find that the ten nonprofit-sector theories continue to be an important foundation for nonprofit studies research. The most commonly used sector theories are associationalism, contract failure, nonprofit/government interdependence, and social origins. However, their analysis suggests that use of the nonprofit-sector theories is merely ceremonial. Nonprofit scholars could do much more to question, develop, and refine the existing sector theories – or to develop new ones. This research highlights the importance of a book like this one to encourage scholars to discuss and question existing sector theories and pose new sector-theory contributions to better understand the nonprofit sector.

This chapter focuses on the frameworks, or theories, that relationship scientists use to guide their study of romantic relationships. The chapter first explains evolutionary theory, which assumes that modern relationships reflect ingrained sex-specific adaptations to challenges derived from differential parental investment and affecting reproductive success. Next, the chapter reviews attachment theory, which contends that humans have an evolved attachment behavioral system that activates under threat and keeps people close to caring others. Attachment theory also explains how child–caregiver relationships can bias this attachment system, creating individual differences that persist into adulthood. A next major theory, interdependence theory, suggests that people rationally attempt to maximize their outcomes, though transformation of motivation can lead them to prioritize relationship outcomes as well. Finally, social ecological models highlight the role of the environment – and particularly stressful environments – to influence interpersonal dynamics. This chapter reviews, critiques, compares, and integrates each of the major theories that support relationship science.

Insecurely attached people have less happy, more unstable romantic relationships, but the quality of their relationships should depend on how their partners regulate them. Some partners find ways to buffer (emotionally and behaviorally regulate) insecurely attached individuals, which can make them feel better, behave more constructively, and improve their relationships. Understanding when, how, and why this important interpersonal process works requires a dyad-centered approach. In this chapter, we first review key tenets of attachment theory and the two primary forms of attachment insecurity (anxiety and avoidance). We then discuss the Dyadic Regulation of Attachment Insecurity Model, which outlines how and why certain types of buffering behaviors should soothe the worries and improve the relationship perceptions and behaviors of highly anxious and highly avoidant people. Following this, we discuss recent studies that illustrate some of the ways in which partners can successfully buffer the insecure reactions of highly anxious and highly avoidant individuals and how they can develop and maintain more “secure” environments. We conclude by suggesting future studies that might extend these recent findings and compare our model with some of the core concepts of Emotion-Focused Therapy.

People often use relationships to characterize and describe places. Some places are described as warm, friendly, and welcoming. Others as cold, harsh, and unwelcoming. Is there any truth to these colloquialisms? How influential is the broader geographic context in affecting our close relationships? Where do people have the happiest relationships and why? In this chapter, I review recent research on geographic variation in relationship-related constructs and outcomes. The review will also feature some empirical examples and methodological considerations for studying geographic variation in close relationships and how they are expressed. A large portion of the chapter will be a discussion on the mechanisms that give rise to geographic variation in relationship-related constructs and behavior that unfold over different time scales. Step-by-step modules and supplementary information for asking geographic questions at different levels of analysis will be provided. Finally, I will conclude with unanswered conceptual and methodological questions related to the study of geographic variation in close relationship behavior.

Romantic relationships affect the levels of security that people generally experience with close others. Experiences with a partner carry immediate outcomes (e.g., feeling appreciated vs. ignored), but they also can have longer lasting effects when they cause people to reflect on their overall worthiness and comfort with closeness/trust toward others. Our chapter examines how such experiences shape the mental representations that underlie chronic tendencies with attachment security, and how these representations may change with new experiences in romantic involvements. We examine change through the lens of the Attachment Security Enhancement Model, which suggests that enhancing security in relationships involves both mitigating momentary insecurity and fostering more secure mental representations over the longer term. Whether partners are effective at enhancing security may depend on the strategies they enact, and optimal strategies depend on whether a person is experiencing momentary anxiety versus avoidance. Over time, partner strategies in new situations – especially those that depart from past insecure experiences (e.g., painful interactions in close relationships) – can lead to revisions of insecure mental representations (e.g., beliefs about the self, expectations of close others). Together, using strategies to manage insecure moments and create opportunities to revise insecure mental representations may enhance security across time.

Contemporary interdependence perspectives posit that intimates are more likely to remain in a relationship to the extent that they are committed to that relationship, and that they tend to be more committed to the extent that they a) are currently satisfied with the relationship, b) believe they do not currently have more desirable alternatives to the relationship, and c) have previously invested resources into the relationship. At times, though, intimates may expect that their relationship satisfaction, alternatives, and investments will increase or decrease in the future, and research on decision-making suggests that such expectations may determine their relationship commitment more than their current or past experiences do. In this chapter, we first identify factors (e.g., plans to improve the relationship, personality, gender) that may cause intimates’ expected experiences to diverge from their current experiences. Next, we review theoretical and empirical work suggesting that intimates’ relationship commitment should be determined more by their expected experiences than by their current or past experiences. Finally, we introduce a new measure of expected relationship satisfaction, alternatives, and investments designed for future research into these ideas.

How do people maintain their closest relationships? In this chapter, we present an interdependence account of how people maintain their relationships with others. Interdependence theory, first articulated by Thibaut and Kelley, was formulated to explain how people choose among potential courses of action in interdependent situations featuring problems of actor coordination and decision-making. Because romantic partners are often faced with daily choices within their relationship (e.g., Should we go to the movie my partner wants to see rather than what I want to see? Should I stay in this relationship or pursue an alternate?), interdependence theory is well suited for understanding relationship maintenance processes. We begin by discussing why relationship maintenance is necessary. We then review the set of processes – behavioral and cognitive – that help keep interdependent relationships intact, despite the fact that situational actors must adapt to constantly changing situations. Central to these processes is one’s commitment to a relationship, which, once established, causes maintaining a relationship to become an automatic, default option under ordinary circumstances.