This article considers how 3 fundamental concepts of second language acquisition (SLA), the native speaker, interlanguage, and the language learner have fared since Firth and Wagner (1997). We review the ascendancy of these concepts and their relationship to the traditional dichotomies of language learning versus language use and individual mind versus social-context-as-environment. We discuss geopolitical changes of the 1990s and the related theoretical shifts from structuralist theories to discourse-based and constructionist social theories, which paved the way for Firth and Wagner. We examine subsequent efforts to reframe SLA as social process and knowledge as social action, arguing that such notions as collaborative dialogue, affordance, and investment have reconceptualized the concepts of output, input, and motivation without, however, escaping their structuralist roots. Looking at data from multilingual exchanges between immigrants recorded in shops in California, we suggest that 3 fundamental concepts be treated as discursive, socially, and historically relative categories, with the subject position of the researcher factored in. (Contains 4 tables.)