This broad survey of research on instructional television examines a variety of aspects relating to its effectiveness in the classroom. An introductory essay identifies significant trends that have emerged since the original publication of this report. Chapter one reviews the generalized effects of TV on pupil learning, including variations in effect caused by the age of the students and by the subject matter being taught. Chapter two outlines what has been learned about the efficient use of TV in a school system. In chapter three, thirty variables important to the effectiveness of television teaching are analyzed. Among these variables are: physical variations in the broadcast and viewing conditions; the length and timing of broadcasts; the use of humor; the teacher's role in televised instruction; and factors affecting student response to TV. Staff and student attitudes toward the use of television are considered in chapter four, while chapter five is devoted to educational television in developing nations. The effectiveness of instructional radio and other media in the learning process is also briefly considered. (SL)