Employing a large panel of over one million firm‐years, I find evidence consistent with widespread compliance with law among U.S. private foundations despite the absence of many formal deterrence mechanisms. The research design exploits rolling state adoption of the Uniform Prudent Management of Institutional Funds Act, which lifted some existing limits on firm spending for a fraction of firms within each state. This allows the use of triple‐difference estimates that control for changes in local norms and economic conditions. UPMIFA increases firm spending, on average, implying that firms were complying with the pre‐UPMIFA regime. Interacting the triple‐difference factors with other predictors of compliance reveals no correlation between compliance and enforcement intensity, but some evidence that compliance is correlated with firm culture and reliance on accountants. These findings have potentially important implications for the governance of charitable organizations, and may speak more generally to drivers of compliance among other organizational forms.