In an increasingly integrated world economy, countries may have greater incentives to weaken environmental policy as disguised protection intended to give a competitive edge to local firms. This may generate pollution havens as firms relocate in response to different environmental policies. Foreign direct investment (FDI) weakens profit-shifting policy considerations while increasing environmental damages but, at the same time, may provide external benefits. We derive conditions under which the FDI-recipient country has an incentive to manipulate its environmental standard to prevent or attract FDI, potentially eliminating or creating pollution havens, in addition to examining the impact of FDI on the equilibrium state of the environment.