This document summarizes a case study on the role of radio-based extension services in Malawi. It outlines the history of radio use in agricultural extension in Malawi since 1958. Key lessons learned from projects run by Farm Radio Trust focusing on participatory radio campaigns include: (1) radio can increase farmers' knowledge and improve agricultural practices, (2) radio is most effective when programs are developed with farmer input, and (3) radio can trigger demand for improved face-to-face extension and other support services. The case study highlights the importance of partnerships between farmers, researchers, extension workers, policymakers, and broadcasters in designing effective radio programming.