ABSTRACT: For some time IBM Research has been developing and testing computer based learning environments for language instruction. Such systems hold great potential in principle because they can provide more individually supervised practice than could possibly be attained in a conventional instructional setting. Training gains will not, however, result from the mere use of a computer but from a clear view of the relation among several essential components of instruction, components which are valued equally both for computer-assisted and classroom instruction. Foreign language learning requires extensive supervised practice effectively addressing relevant aspects of linguistic competence and performance. The central focus of foreign language teaching must be on the construction of a learning environment in which students will purposefully undertake activities through which they will master the subject matter. For language learning, the critical elements of a learning environment are (1) acceptable content, (2) a readily comprehensible mediational system allowing a student to perform relevant learning tasks, and (3) a supervisory system structuring and assigning learning tasks on an individual basis. The large training gains observed in a major experiment conducted at Stony Brook (SUNY) last year are attributable, it is believed, to the adequacy of these components in the computer-assisted instruction system developed for the study.