Resources for research and development activities are limited and, therefore, it is important to accurately target research work and technical interventions to the true needs and opportunities of farmers, processors, or traders. This paper details the use of needs-assessment techniques to assess the constraints and opportunities in post-harvest systems. Two examples of needs-assessment studies and subsequent adaptive research and technology dissemination activities, are presented to demonstrate the use of needs assessment in the planning and implementation phases of the project cycle. The examples are taken from work in Tanzania and Uganda. Needs-assessment techniques have the potential to improve the relevance of post-harvest research and development and are recommended as part of a participatory approach to prioritising research, technology generation, and diffusion. The methods do, however, have their weaknesses and shortcomings and these are discussed.