Two types of feedback are examined, and their use in controlling the processes of instructional development and improvement are discussed. Closed-loop feedback, the most direct, uses immediate feedback about a process or product to make immediate adjustments in it. Open-loop feedback, in which input cannot be changed immediately, uses feedback to make changes in a subsequent event. The consequences and applications of these two types of control for language teaching methodology, and specifically for languages for special purposes, are explored. The 2 control types are seen as related to instructional approaches, teacher-proof and teacher-autonomous, which have implications for materials, instructional need analysis, course design, evaluation, and the role and introduction of feedback in the classroom. The integration of feedback, evaluation, and learning is illustrated in the process of teaching a study skill, summary-writing. Appended materials include a checklist on classroom feedback management for teachers, instructions for teaching summary-writing, the Portuguese version of such a unit taught to electronics technicians, and a personal recording card to help students and teachers assess their own learning throughout the course. (MSE)