Dynamically and statically optimal Pigouvian subsidies and taxes on durables will differ in a growing economy. In a dynamic game, consumers may delay purchasing durables with positive externalities, such as latrines, anticipating greater future subsidies. Governments can most cheaply induce optimal purchasing by commiting to make subsidies temporary. Foreign donors may make commitment impossible, generating delays in private investment that more than fully offset the social benefits of transfers. Anticipated future taxes or regulation of durables with negative externalities, such as guns, may encourage current purchase, potentially causing policymakers who would otherwise prefer taxes or regulation to abandon such policies.

Do land market frictions cause misallocation in agriculture? In a field experiment in western Kenya, we randomly subsidize owners to rent out land. Induced rentals mostly persist after the subsidy ends and increase output and value added, consistent with misallocation. Gains from trade arise from renters choosing higher-value crops, having higher productivity, and adopting more nonlabor inputs, while renters use similar quantities of labor as owners. Induced rentals are not those with the largest predicted gains, underlining the importance of the joint distribution of gains and frictions, with frictions arising from search, risk, and learning.(JEL C93, O13, O18, Q12, Q15, Q24, R52)