["Journal of Agricultural Economics, EarlyView. ", "\nABSTRACT\nSmall seed packs for demonstration and testing are widely used to stimulate the uptake of improved crop varieties, yet evidence on their effectiveness remains mixed. This study examines whether small seed packs distributed either for free or at a subsidised price enhance farmers' knowledge and subsequent adoption of improved legumes, drought‐tolerant maize, and improved traditional African vegetables in Tanzania and Zambia. Drawing on mobile phone survey data and applying entropy balancing alongside machine‐learning methods to address selection bias, we find consistent evidence that seed packs increase both technical knowledge and adoption of these crops. Knowledge gains are strongest for crops with limited prior exposure, while improvements for familiar crops such as drought‐tolerant maize likely reflect experiential learning rather than new information. Adoption effects are positive across all crops and robust to alternative estimation strategies. Overall, the results indicate that small seed packs can serve as an effective demand‐creation tool, particularly in settings where farmers face information gaps or uncertainty about the performance of improved germplasm.\n"]