Although inter‐cropping (IC) is widely practised in rainfed tropical small‐scale agriculture, agricultural research scientists have not systematically explored the rationale for it and have rarely attempted to improve it. instead, they have concentrated on planting crops in pure stands and extension advice has been to replace IC with pure stands. This has reduced the impact of research and extension activities. A review of East African experience from the 1930s considers reasons for the research concentration on pure stand planting and reveals two phases when formal experiments on IC were carried out. Despite generally favourable results, neither of these led to including IC in extension advice to farmers. IC can contribute to one or more of five common objectives of small‐scale farmers, but the standard design of agronomic experiments at best takes account of only one of these, so that benefits are underestimated and erroneous policy conclusions drawn. The paper advocates, inter alia , multidisciplinary research for small‐scale agriculture and active participation by farmers themselves.