This report describes the activities of the Radio Mathematics Project of the Institute for Mathematical Studies in the Social Sciences (IMSSS) during the 1974-75 fiscal year. This project is funded by AID for the purposes of (1) developing and testing a cost-effective system of radio instruction in elementary mathematics for developing countries, (2) developing a methodology for producing radio materials based on rapid feedback concerning student performance, (3) beginning a program of research on learning by radio, and (4) helping a host institution develop the capability to continue or expand the program. The second year of the project, beginning July 1974, was devoted primarily to testing the system and training teachers in Masaya, Nicaragua. These activities and their results are described in this document. (SD)