It has recently been suggested that bilingualism, rather than age of acquisition, is what underlies less than nativelike attainment in childhood L2 acquisition. Currently, however, the empirical evidence in favor of or against this interpretation remains scarce. The present study sets out to fill this gap, implementing a novel factorial design in which the variables age of acquisition and bilingualism have been fully crossed. Eighty speakers of Swedish, who were either L1 monolinguals, L1 simultaneous bilinguals, L2 sequential monolinguals (international adoptees), or L2 sequential bilinguals (childhood immigrants), were tested on phonetic, grammatical, and lexical measures. The results indicate consistent effects of age of acquisition, but only limited effects of bilingualism, on ultimate attainment. These findings thus show that age of acquisition – not bilingualism – is the primary determinant of L2 ultimate attainment.

This study explored the long-term effects of limited input on bilingual teenagers’ acquisition of complex morphology in Welsh. Study 1 assessed 168 12–13 and 16–17-year-old teenagers, across three bilingual groups: those whose first language was Welsh (L1 Welsh), those who learned Welsh and English simultaneously (L1 Welsh–English), and those who learned Welsh as a second language (L2 Welsh), on their receptive knowledge of grammatical gender. Study 2 assessed the same participants on their production of plural morphology. While the results of Study 1 revealed continuous progression toward adult norms among L1 Welsh-speaking bilinguals, with the simultaneous bilinguals progressing at a slower rate, the results of Study 2 revealed performances on plural morphology that were comparable to adult norms among the 16–17-year-old L1 Welsh-speaking bilinguals, and some progression among the simultaneous bilinguals. In contrast, delayed progression was seen among the L2 Welsh-speaking bilinguals across the board, with 16–17-year-old L2 participants lagging behind their L1 peers on both grammatical gender and plural morphology. The implications of these findings for our understanding of the long-term outcomes for bilinguals learning complex structures under minority language conditions are discussed.

Mayberry and Kluender (2017) offer a rich review of empirical research that contributes to the understanding of age-related effects on first and second language acquisition. Their keynote article compiles current, primarily linguistic and neurolinguistic, research on the notion of a critical period for language (CPL). The authors conclude “that the putative CPL applies to L1 learning, and that L2 effects are a consequence of this prior learning” (Mayberry & Kluender, 2017: p. 6). As they propose a clear role for CPL in L1 learning, and because their exact position on its role in L2 learning is, to my mind, not as clearly articulated, I will take the opportunity to argue the following: If a CPL exists at all, it should have identifiable implications for all kinds of language acquisition (cf. Gleitman & Newport, 1995). In the case of L2 acquisition what needs to be identified is how maturational constraints (implicated by a CPL) interact with other conditions that are at hand when the second language comes onto the scene.

Mayberry and Kluender (Mayberry & Kluender) adopt interesting positions on a wide range of issues. Due to space limitations, we will focus on just two where our views differ: (i) the robustness of maturational constraints on second language acquisition (L2A), and (ii) the implications of a role for language aptitudes within the boundaries defined by sensitive periods (SPs).

In this paper we show that heritage speakers and returnees are fundamentally different from the majority of adult second language learners with respect to their use of collocations (Laufer & Waldman, 2011). We compare the use of lexical collocations involving yap- “do” and et- “do” among heritage speakers of Turkish in Germany (n = 45) with those found among Turkish returnees (n = 65) and Turkish monolinguals (n = 69). Language use by returnees is an understudied resource although this group can provide crucial insights into the specific language ability of heritage speakers. Results show that returnees who had been back for one year avoid collocations with yap- and use some hypercorrect forms in et-, whilst returnees who had been back for seven years at the time of recording produce collocations that are quantitatively and qualitatively similar to those of monolingual speakers of Turkish. We discuss implications for theories of ultimate attainment and incomplete acquisition in heritage speakers.