This special issue revisits a classic topic in linguistic theory, A-bar movement, applied to developing and bilingual grammars. We claim that A-bar movement, or filler-gap dependencies, is still the quintessential linguistic phenomenon to illustrate the interaction between the biological endowment, the experience with language (past and present),…

This provocative article raises many important issues that need to be addressed and in so doing will advance the fields of second language (L2) and third language (L3) acquisition in several important ways. Fundamental questions concerning multilingual development persist especially with respect to the role of Universal Grammar in this language…

In her keynote article advocating the Linguistic Proximity Model for third language (L3) acquisition, Westergaard (2021) presents several arguments against 'copying and restructuring' in nonnative language acquisition, mechanisms central to Schwartz and Sprouse's (1996) Full Transfer/Full Access model of second language (L2) acquisition. In this…

This commentary discusses the recent keynote article in "Second Language Research" by Westergaard (2021), which extends the Micro-cue Model to second language (L2) and third language (L3) acquisition. The commentary comments on such questions as: What makes a given property easy or hard to acquire? How do learners determine similarity?…

In this commentary, I suggest that it may be helpful to think about the formidable problem space that Westergaard's (2021) Linguistic Proximity Model seeks to address at the three levels of analysis that Marr (1982) famously proposed are needed to understand any complex cognitive system. I argue that at the computational level of analysis, where…

In this article, I argue that first language (L1), second language (L2) and third language (L3) acquisition are fundamentally the same process, based on learning by parsing. Both child and adult learners are sensitive to fine linguistic distinctions, and language development takes place in small steps. While the bulk of the article focuses on…

Amaral and Roeper (this issue; henceforth A&R) argue that all speakers -- regardless of whether monolingual or bilingual -- have multiple grammars in their mental language representations. They further claim that this simple assumption can explain many things: optionality in second language (L2) language behaviour, multilingualism, language…

The central claim in Amaral and Roeper's (this issue; henceforth A&R) keynote article is that everyone is multilingual, whether they speak one or more languages. In a nutshell, the idea is that each speaker has multiple grammars or "sub-sets of rules (or sub-grammars) that co-exist". Thus, rather than positing complex rules to…

This paper presents an extension of the Multiple Grammars Theory (Roeper, 1999) to provide a formal mechanism that can serve as a generative-based alternative to current descriptive models of interlanguage. The theory extends historical work by Kroch and Taylor (1997), and has been taken into a computational direction by Yang (2003). The proposal…

This article examines the third language (L3) developing morphology of 78 Basque-Spanish bilinguals following a Content and Language Integrated Learning (CLIL) program and a mainstream English as a foreign language (non-CLIL) program. The analysis of cross-sectional and longitudinal oral data shows that (1) the omission of inflection in the L3…