In the past century major changes in the study of language learning, and its attendant effects on language instruction, derived from the espousal of behavioral psychology by structural linguistics of the Bloomfieldian persuasion. Did not the founder of this strand of structuralism, who collaborated in the Army language manual for the teaching of Russian under the revealing pseudonym of I. M. Lisnin, declare: “Language learning is overlearning, nothing else is of any use”? Noam Chomsky's (1959) brilliant demonstration of the reductionism of the most extreme form of behaviorism—Skinner's operant conditioning (Review of B. F. Skinner's Verbal Behavior, Language, 35, 26–58)—triggered the demise of the influence of behavioristic views of language acquisition. This demise was accompanied by that of the structural approach to second language teaching associated with such applied linguists as Robert Lado, although it must be acknowledged that the combination of these two theoretical strands did lead to significant changes in foreign language classrooms—for example, the abandonment of grammar translation and a shift of focus from written texts to speech. However, what applied linguists of that generation failed to do was to observe how actual second language learners in both naturalistic and instructed contexts process and reorganize linguistic input, how they intake it, and how they turn it into output in communicative interactions. It was not until the impact of Chomskian-inspired studies of first language acquisition and Pit Corder's (1967) seminal “The significance of learners' errors” (International Review of Applied Linguistics, 5, 161–170) that the second language learner came into focus and that the field of second language acquisition research began to flourish. In this connection, it is noteworthy that bringing to a wider international audience the proceedings of the Neuchâtel colloquia led by Corder served as a catalyst for the launching of SSLA.