Adult illiteracy is a worldwide problem. Illiterate adults are the most difficult to teach and to reach because illiteracy is characterized by embarrassment and low self-esteem. Given that radio is heavily used by lower income and less educated people, literacy projects utilizing radio were attempted in 40 countries between 1960 and 1974. The main roles for broadcasting in these projects have been to (1) raise awareness of politicians of the need for and benefits of program provision; (2) recruit potential students and volunteers to projects; and (3) provide audiovisual materials to assist face to face tuition. Latin American radio schools have used radio didactically, as the main medium of instruction, unlike other countries. There is no single homogeneous audience for adult literacy programming, but a variety of open and closed audiences. There are also major differences in interest between urban and rural audiences, men and women, and young and old audiences, which provides a major programming challenge to radio literacy producers. Another important factor of European projects is close coordination and cooperation between broadcasters and other agencies. Worldwide experience suggests four basic models of radio ownership and control: commercial, public broadcasting, open access, and radio schools. The models have profound implications for the way radio is used for adult literacy. More published evaluation data are needed on the effectiveness of the radio schools in teaching literacy. In addition, world experience suggests that the use of radio for adult literacy must be accompanied by social, economic, and political reform. (NLA)