Children acquiring their first languages are frequently regarded as the principal agents of diachronic change. The causes and the precise nature of the processes of change are, however, far from clear. The following discussion focuses on possible changes of core properties of grammars which, in terms of the theory of Universal Grammar, can be characterized as reflecting different settings of parameters. In such cases, learners develop grammatical competences differing from those of speakers of the previous generation who provided the primary data serving as input for the developmental processes. It has been argued that reanalyses of this type must be conceived of as instances of transmission failure. Yet acquisition research has demonstrated that the human Language Making Capacity is extraordinarily robust, thus leading to the question of what might cause unsuccessful acquisition. Changing frequencies in use or exposure to data containing ambiguous or even contradictory evidence are unlikely to suffice as causes for this to happen. Language acquisition in multilingual settings may be a more plausible source of grammatical reanalysis than monolingual first language development. The study of contemporary bilingualism can therefore contribute to an explanation of diachronic change. Yet one such insight is that simultaneous acquisition of two languages (2L1) typically leads to a kind of grammatical knowledge in each language which is qualitatively not different from that of the respective monolinguals, obliging us to look for other sources of transmission failure. 2L1 acquisition in settings where one language is “weaker” than the other has been claimed to qualify as such. But I will argue that even such problematic cases do not provide convincing evidence of reanalysis. If, on the other hand, children receive sustained input from second language learners, or if their onset of acquisition is delayed, this can indeed lead to incomplete acquisition. I conclude that successive acquisition of bilingualism plays a crucial role as a source of grammatical change. In order for such changes to happen, however, grammar-internal and language-external factors may have to concur.

Jürgen Meisel argues that “grammatical variation. . .can be described. . .in terms of parametric variation”, and – crucially for his arguments in this paper – that “parameter settings do not change across the lifespan”. To this extent he adopts the standard generative view, but he then departs from what he calls “the literature on historical linguistics” (by which he means the generative literature only) in developing the arguments leading to his major claims: that only “transmission failure” resulting from L2 acquisition can produce parametric morphosyntactic change; that any L2 learners, children or adults, may be the agents of change; that such changes “happen less frequently than is commonly assumed”; and that, “in larger and more complex societies, situations in which L2 learners exert a major influence on a language are most likely to emerge in periods of substantial demographic changes” (his example is a plague that kills most members of a speech community). Adult L2 learners, according to Meisel, can only be agents of parametric change if they provide most or all of the input for the next generation's L1 acquisition.

There is a long linguistic tradition in which language change is explained in terms of first language acquisition. In this tradition, children are considered to be the agents of language change, or at least the agents of changes in the underlying grammar. Since the early 1980s, this has been formulated in the (generative) terminology in terms of parameters set by children: whereas an older generation acquires one particular setting of a parameter (during childhood), a next generation of L1 children may set a parameter differently, based on the input of their parents, and this may lead to a different output. For obvious reasons this argumentation had to be built on theoretical rather than empirical work on language acquisition. There are no children acquiring Old English or Middle Dutch, and, in fact, the field of acquisition research was until recently much less developed and very often not focused on the type of facts that happened to play a role in discussions of language change.

Jürgen Meisel's (JM) article is literally thought-provoking, especially for the issues that one can raise out of the central position that he develops, viz., “although bilingual acquisition in situations of language contact can be argued to be of significant importance for explanations of grammatical change, reanalysis affecting parameter settings is much less likely to happen than is commonly assumed in historical linguistics” (p. 142). This is a position that calls for grounding language change, hence historical linguistics, in the pragmatics/ethnography of language practice, a question that linguists can continue to ignore no more than the actuation question (Weinreich, Labov & Herzog, 1968; McMahon, 1994; Labov, 2001; Mufwene, 2008). The latter regards what particular ethnographic factors trigger particular changes at particular places and at particular times but not at others. In other words, do structural changes happen simply because they must happen or because particular agents are involved at specific times under specific ecological conditions of language practice?

Meisel (hereafter, M) has offered a well-argued and tightly structured piece, discussing in a clear and compelling way a crucial topic in the understanding of language change. I applaud him for both the content and the presentation.

Bilingual first language acquisition (BFLA) has been considered a possible mechanism of contact-induced change in several recent studies (Siegel, 2008, p. 117; Satterfield, 2005, p. 2075; Thomason, 2001, p. 148; Yip & Matthews, 2007, p.15). There is as yet little consensus on the question, with divergent views regarding both BFLA at the individual level and the implications for language change at the community level.

If one asks how many languages there are, one can imagine at least three answers: one, over six billion, or 7,358.

The starting hypothesis of the keynote article (KA) is that language acquisition plays an essential role in processes leading to grammatical change. Consequently, a minimal requirement, to be met by explanations of diachronic change is that they rely on mechanisms which are operative in acquisition. The KA is therefore an appeal for interdisciplinary cooperation between historical linguistics and acquisition research.

Previous research has reported that bilingual children sometimes produce mixed noun phrases with ‘correct’ gender agreement – as in der dog (der being a masculine determiner in German and the German word for “dog”, hund, being masculine as well). However, these could obviously be due to chance or to the indiscriminate use of a default determiner. In the current study, we established with high statistical reliability that each of three German–English bilingual children, of 2–4 years of age, produced such mixed NPs with ‘correct’ agreement at significantly greater than chance levels. Also noteworthy was the fact that all three children produced such NPs with German determiners and English nouns much more frequently than the reverse. These findings provide a solid statistical foundation for further studies into the phenomenon of mixed noun phrases with ‘correct’ gender agreement.

The present study compares the relative effect of inherent lexical aspect and discursive grounding on the use of L2 Spanish Preterit and Imperfect. The study is based on the analysis of responses to a written 40-item discourse-based forced-choice task among 286 English-speaking learners of Spanish. The analysis of data (repeated measures ANOVA) reveals that as learners gain more experience with the target language, the effect of both lexical aspect and grounding on past tense marking increases. That is, contrary to previous predictions, learners constantly move towards prototypical associations of lexical-narrative factors with morphological markers as knowledge of the second language increases. Second, grounding is the construct that most clearly distinguishes learners from native speakers.

Second language acquisition studies can contribute to the body of research on the influence of language on thought by examining cognitive change as a result of second language learning. We conducted a longitudinal study that examined how the acquisition of Spanish grammatical gender influences categorization in native English-speaking adults. We asked whether learning the grammatical gender of Spanish affects adult native English speakers' attribution of gender to inanimate objects. College students enrolled in beginning Spanish participated in two tasks repeatedly (four times) throughout one academic year. One task examined their acquisition of grammatical gender. The other examined their categorization of inanimate objects. We began to observe changes in participants' grammatical gender acquisition and in categorization after ten weeks of Spanish instruction. Results indicate that learning a second language as an adult can change the way one categorizes objects. However, the effect of Spanish grammatical gender was more limited in Spanish learners than in native Spanish speakers; it was not observed for all kinds of objects nor did it increase with learners' proficiency, suggesting that adults learning Spanish reach a plateau beyond which changes in categorization do not occur.

Can transfer occur in child bilingual syntax when surface overlap does not involve the syntax-pragmatics interface? Twenty-three Spanish/English bilingual children participated in an elicited imitation study of clitic placement in Spanish restructuring contexts, where variable word order is not associated with pragmatic or semantic factors. Bilingual children performed poorly with preverbal clitics, the order that does not overlap with English. Distinct bilingual patterns emerged: backward repositioning, omissions (for simultaneous bilinguals) and a reduction in forward repositioning bias. We conclude that transfer should be defined in lexical terms as the result of priming effects leading to shifts in lexical items.

An increasing number of schools offer bilingual programs, where lessons are taught in more than one language. Several theories state that bilinguals have greater metalinguistic awareness than monolinguals. We investigated whether this greater metalinguistic awareness is also related to an increased ability to understand an unknown language. To measure metalinguistic awareness and the ability to understand text written in an unknown language, we designed the Indonesian Language Test (ILT). The ILT consists of items regarding a story in Indonesian. Dutch high school students from monolingual and bilingual classes were administered the ILT, a Dutch Language Test, an English Language Test, and a general intelligence test. The ILT showed promising psychometric properties. Bilingual students scored significantly higher on the ILT than monolingual students. Multi-group confirmatory factor analyses showed (i) that ILT measures the ability to understand an unknown language, and (ii) that bilingual students score significantly higher than monolingual students on this ability. Both observations support the notion that bilingual education increases metalinguistic awareness and therefore the ability to understand an unknown language.

This research examines the processes which native Spanish-speaking learners of English and English-only students engage in when inferring meaning for unknown English words that have Spanish cognates. Conducted within the context of a large-scale vocabulary intervention that taught word inferencing strategies, including a cognate strategy, this qualitative study describes cognate strategy use among a small sample of participants. The data suggest that explicit instruction, students' metalinguistic and metacognitive skills, and the structural characteristics of cognate pairs are associated with cognate recognition.