This article examines the effect of participatory governance on policy performance in the United States, which is shaped by external and internal factors related to transaction cost. Externally, if transaction-cost-related policy conditions are uncertain-thereby increasing transaction cost-the effect of participatory governance on policy performance is less positive. Internally, noninstitutionalized participatory governance methods (e.g., public meetings) are less effective than institutionalized ones in improving policy performance (e.g., advisory committees). In addition, these internal and external factors affect the choice of participatory governance methods by government agencies: agencies are more likely to employ institutionalized participatory governance methods under low-transaction-cost policy conditions.