We use a randomized evaluation of a deworming program in Kenya to examine peer effects in technology adoption and to shed light on foreign aid donors’ movement towards helping communities sustainably provide local public goods. Deworming is a public good, since much of the social benefit of worm treatment comes through reduced disease transmission. People were less likely to take deworming drugs if their direct first-order social contacts or indirect secondorder contacts were randomly exposed to deworming. Several efforts to replace subsidies with sustainable worm control measures were ineffective: a drug cost-recovery program reduced takeup by 80%; health education did not affect behavior, and a mobilization intervention designed to boost drug take-up failed. At least in this context, it appears unrealistic for donors to think that a one-time intervention can lead to the sustainable voluntary provision of local public goods.