Does environmental enforcement actions, including states’ strategic responses to neighbors’ policy choices, depend on governor party affiliation? Do governors of different parties use environmental policy instruments differently? Our paper addresses these questions. Accounting for endogeneity and omitted variable biases, we find that Democratic governors on average depress overall inspection rates versus their Republican counterparts, but not the frequency of punitive actions (except in the South). Strategic responses to neighbors do not depend on party affiliation. Finally, treating party affiliation as endogenous and allowing for strategic interaction effects both appear important for our estimations.