In environmental, health and development contexts, policymakers often subsidize and distribute goods that generate positive externalities, only to see these goods subsequently disadopted. We posit that disadoption of these pro-social goods can be reduced by longer exposure to the goods when longer use enhances the goods’ perceived net benefits. In a randomized trial, four months of incentivized exposure increased the likelihood that a household was still using low-flow water fixtures one year after incentives were no longer offered. We articulate a unified theoretical framework for understanding the mechanisms of exposure-enhancement—i.e., changes to information, taste, and ability—and apply the framework to the experimental data. Longer exposure provided households with better information on water bill savings and increased households’ taste for the fixtures. It did not appear to have improved the ability of households to maintain the fixtures. The theory and results imply that short-term exposure incentives for pro-social goods can serve, in some cases, as alternatives to more popular purchase subsidies or ongoing use subsidies.