Many development programs are short-term interventions, either because of external funding constraints or an assumption of impact sustainability. Using a novel randomized phaseout research method, we provide experimental tests of phaseout effects of an extension program designed for women smallholder farmers in Uganda. We find that program phaseout does not diminish demand for improved seeds, as farmers shift purchases from NGO-sponsored village supply networks to market sources, indicating persistent learning effects. We find no evidence of declines in improved cultivation practices taught by the program. These results have implications for both efficient program design and for models of technology adoption.