A cost-effectiveness study in the teaching of foreign languages would, if implemented, aim to determine the results of cost-effectiveness by the introduction of new aims, methods, and equipment; to estimate the efficacy of existing resources; and to examine any other means by which productivity per student-cost could be improved. The following concepts, related to cost-effectiveness, are studied in this paper: observable change, costs, benefits, system, capital and other expenditures, value, wastage, productivity, terminal standards, programed learning, and product value change assessment. Causal relationships and areas for systems improvement are stressed. The author suggests that such a study would advance the goals of applied linguistics. (RL)