The Radio Language Arts Project, a five-year research and development effort funded by the U.S. Agency for International Development in cooperation with the Kenya government to systematically assess the costs and benefits of intensive use of radio as the principal vehicle for primary level English instruction in rural areas of Kenya, is described and discussed. The potential of radio as the main instructional medium in a formal educational setting is discussed, and an example from Nicaragua of the successful realization of this potential is noted. The subject matter, English, is analyzed from the perspective of the radio as medium, and the most significant instructional design principles used in the Radio Language Arts Project are enumerated. Formative and summative evaluation strategies for the project are discussed, and the initial results are outlined. (MSE)