A discussion of the task-based approach to second language learning looks at different interpretations of "task" and defines it in terms of two basic dimensions: (1) degree of learner involvement in purposeful work, and (2) a continuum from focus on linguistic form to focus on message. It is proposed that these dimensions can be understood better through insight from two areas of cognitive psychology. The first of these accounts for learning through social interaction, and how language is acquired in the context of social and cognitive development. The second is concerned more specifically with how knowledge comes to be represented in the mind and how it becomes available as a basis for performance. It is suggested that with further refinement and research, these areas of cognitive psychology could offer additional insights into the use of tasks in foreign language instruction. (Contains 35 references.) (MSE)