This study investigated the morphosyntax of adjectival concord in case and number and subject-verb person agreement by monolingual and bilingual speakers of Russian. The main focus of the study is on the potential factors that may trigger divergence between Heritage Language (HL) speakers and those speakers who are dominant in that language, be they monolingual or bilingual. We considered the effects of cross-linguistic influence; limited input (as indexed by Age of Onset of Bilingualism, AOB), and working-memory limitations. An auditory offline grammaticality judgment task was performed by 119 adult participants split into four groups: (1) Monolingual Russian-speaking controls (MonoControl), (2) Immigrant Controls, that is, Russian-Hebrew bilinguals with AOB after the age of 13 (IMMControl); (3) bilinguals with AOB between 5–13 (BL-Late); and (4) bilinguals with AOB before the age of 5 (BL-Early). The latter group represents HL speakers. We did not find effects of cross-linguistic influence or extra memory load; at the same time, the effects of AOB were robust. Additionally, HL speakers (BL-Early group) differed from the other groups in poor performance on adjectival concord, but patterned with the others on person agreement, which indicates that the feature [person] is more robust than other agreement/concord features in HL grammars.

There has been a substantial amount of research on heritage language acquisition and diachronic change. Although recent work has increasingly pointed to parallels between those two areas, it remains unclear how systematic these are. In this paper, we provide a bird's eye view, illustrating how patterns of diachronic change are mirrored in heritage language grammars. In doing so, we focus on one of the best-described grammaticalization processes – namely, the formation of articles from demonstratives and numerals, reviewing studies on heritage varieties which mirror those processes. Based on this review, we make two main points: that change in heritage language can be predicted based on established diachronic scenarios, and that heritage languages often amplify incipient changes in the baseline. After discussing a number of attested changes in a bilingual context, we identify directions for future research in the domain of determiners in heritage languages.

Our keynote, “Understanding heritage languages” (Polinsky & Scontras, 2019), and the commentaries to it make the following main points.

With a growing interest in heritage languages from researchers of bilingualism and linguistic theory, the field of heritage-language studies has begun to build on its empirical foundations, moving toward a deeper understanding of the nature of language competence under unbalanced bilingualism. In furtherance of this trend, the current work synthesizes pertinent empirical observations and theoretical claims about vulnerable and robust areas of heritage language competence into early steps toward a model of heritage-language grammar. We highlight two key triggers for deviation from the relevant baseline: the quantity and quality of the input from which the heritage grammar is acquired, and the economy of online resources when operating in a less dominant language. In response to these triggers, we identify three outcomes of deviation in the heritage grammar: an avoidance of ambiguity, a resistance to irregularity, and a shrinking of structure. While we are still a ways away from a level of understanding that allows us to predict those aspects of heritage grammar that will be robust and those that will deviate from the relevant baselines, our hope is that the current work will spur the continued development of a predictive model of heritage language competence.