Building on the burgeoning literature on the association between the welfare state and the environmental state, this study empirically examines how the politics of the former has affected the development of the latter. We suggest that the size of the welfare state shapes the calculus of environmental policy costs by partisan governments. A generous welfare state lowers the costs perceived by the left-wing government, as large redistributive spending allows the government to mitigate the adverse impact of the new environmental policy on its core supporters, industrial workers. A generous welfare state also implies diminished marginal political returns from additional welfare commitment by the left-wing government, which lowers the opportunity costs of environmental policy expansion. To the contrary, because of lower overall regulatory and taxation pressure, a small welfare state reduces the costs of environmental policy expansion as perceived by a right-wing government. Our theoretical narrative is supported in a dynamic panel data analysis of environmental policy outputs in 25 Organisation for Economic Co-operation and Development member states during the period 1975-2005.