Research on the role of educational radio in the classroom sponsored by the Agency for International Development over a ten-year period in Nicaragua, Kenya, and the Dominican Republic is reviewed. An introductory section outlines the reasons for using radio for instructional purposes: (1) it is widespread and democratic; (2) serious radio use is still a novelty in most classrooms; (3) it can entertain and teach simultaneously; (4) it can establish a uniform standard of excellence; (5) it can use the best educational methods; (6) it is cost-effective; and (7) it is familiar technology. Four landmark programs are described, including a primary level radio mathematics project in Nicaragua, a five-year language arts project in Kenya, a Dominican Republic basic education program for out-of-school children aged 7 to 14, and a yet-to-be implemented science project. Lessons learned from past experience with instructional radio are examined, and include the potential for its use, how children learn with it, techniques and advantages of intensive use, the need to stimulate pupil participation and immediate feedback, the advantage of using distributed learning principles and devoting each lesson to a variety of topics, enhancing the role of teachers and parents, the availability of low cost instructional aids, and the reliability of equipment. (MSE)