There is an urgent need to quantify which extension methods are most effective in Africa. The objective of this study was to determine the impact of alternative extension methods on adoption of the triple bagging cowpea storage technology in Niger and Burkina Faso. This study was designed as a quasi-experiment with two alternative extension methods studied: village demonstrations and demonstrations reinforced by radio broadcasts. Interview data was collected on triple-bag adoption in villages with the two types of extension programmes and control villages with no storage extension. Binary logit regression analysis was used to identify factors which influenced triple-bag adoption. Storage demonstrations boosted adoption of triple-bag storage by statistically significant marginal probabilities of 34% in Niger and 13% in Burkina Faso, compared to villages with no demonstrations or radio messages. Reinforcement of the demonstration experience with radio broadcasts increased adoption by statistically significant estimates of 23% in Niger and 20% in Burkina Faso. Reinforcement of extension programmes with radio messages is strongly supported by this research. In this case, an already effective demonstration programme was made more effective by associated radio messages. This is an example of evidence based extension that supports decisions on extension programming with quantitative data on the impact of alternatives on behaviour change. (Contains 7 tables and 2 figures.)