A key feature of recent agricultural extension programs has been the focus on increased participation for local, rural communities in the overall decision-making process. This move towards increasing community participation has raised expectations in terms of communication: communication between central research facilities and rural communities, between rural communities and central research facilities, and amongst the rural communities themselves. In order to provide effective communication along each of these channels, attention is turning to the extension trainers deployed in the field. For extension trainers this emerging communication role is distinct from, and supplementary to, the conventional technical training function. The thesis highlights the lack of effective training in communication skills in existing extension training programs. It identifies the flip chart as the most widely used visual aid for farmer training, and the overhead projector as the most widely used visual aid for in-service training. The thesis develops a comprehensive set of training competencies and content for teaching those two technologies, derived from individual task analyses and an extensive literature review. A range of strategic alternatives for the delivery of those competencies in a developing country are then formulated and examined. Central to the different strategies considered is the use of interactive multimedia as a key delivery technology. Two proprietary CDROMs have been designed and produced specifically to the support training in the design and production skills for overhead projector and flip chart technologies. The design, content and production of the CDROMs is described, and both technical and user evaluations are presented. The two CDROMs have been field-tested in Sri Lanka, across a broad range of strategic alternatives. The outcome is a set of guidelines and specific structures for training programs in overhead projector and flip chart technologies. The guidelines are generic and broadly applicable. The case studies also indicate a particular subset of preferred strategies for the future deployment of interactive multimedia-based training in developing countries. Most specifically, the thesis indicates a balance between and the need for mix of interactive multimedia modules along with face-to-face training support / Doctor of Philosophy (PhD)