We evaluate the efficiency of dynamic linked environmental regulation. Linked regulation allows inspectors who uncover violations at one plant to increase future enforcement at other plants that share a common owner. When compliance costs are correlated, regulators can then target scarce enforcement resources towards bad actors without inspecting everyone. We develop an empirical framework of dynamic moral hazard under linked regulation that allows for large portfolios of plants and for choices to be interdependent within the portfolio of plants and across time. Using the framework we evaluate a linked regulation scheme in Texas and find that linked regulation performs substantially better than both unlinked regulation and untargeted regulation. We test two alternative theoretical mechanisms that underpin the benefit—a “firm-wide moral hazard mechanism” and a “correlated targeting mechanism”—and find that a large share of the value of linked regulation is due to the former.