A discussion of the design of effective instructional materials for English as a Second Language (ESL) focuses on the application of second language learning theories and concepts of instructional design from educational technology to development of interactive video. A number of second language learning models and related research are examined, including the cognitive processing, negotiated interaction, and experience models. Current language teaching practices are similarly reviewed, including communicative language teaching approaches, interactive language teaching, and applying what is known about learning strategies and styles to language teaching. Three aspects of research in the field of educational technology bearing on the discussion (the notion of inquiry leading to learning, the systems approach to instructional design, and attributes of courseware for computer-assisted instruction) are then reviewed, and the implications of theory, practice, and instructional design for interactive video are synthesized. A project at National Tsing Hua University (Taiwan) in which these findings were applied in development of ESL courseware on interactive video is then described and illustrated. Ideas for classroom use and considerations in evaluating the materials are discussed briefly. A 49-item bibliography is included. (MSE)