A discussion of research on naturalistic second language acquisition (SLA) focuses on its relationship to the foreign language classroom context. It is argued that to attempt to relate natural SLA to classroom foreign language learning (FLL), a coherent and consistent theoretical framework is needed. The Cognitive-Interactionist Model is developed here. It consists of a model of interlanguage development, the Nativization Model, a set of psycholinguistic processes, and a group of principles that seem to underlie SLA and, it is claimed, FLL. The principles are based on a theoretical framework developed for first language acquisition. The evidence for each principle is discussed, drawing on SLA research for a number of languages. Proposals are made for innovative research that can be conducted in the classroom foreign language context within the Cognitive-Interactionist Model to investigate further the relevance of this model to FLL. A brief examination of the role of interaction and communication strategies in promoting SLA concludes the discussion. A 71-item bibliography is included. (MSE)