The first stage of combinatorial speech is better described as variable than uniform. Talk of variants obscures two different aspects of language (knowledge and use) and two different aspects of language development -- acquisition of the grammar (competence) and deployment of the grammar in speaking and listening (performance). Null subjects and…

This commentary discusses Westergaard's (2021) keynote article, which presents a comprehensive model of first language (L1), second language (L2), and third language (L3) acquisition. The commentary presents evidence from a previous study of L3 learners that provides support for Westergaard's property-by-property transfer proposal. The commentary…