Institutional scholars have argued that in the absence of legislation on the issue of climate change, nongovernmental organizations (NGOs) can help reduce the amount of anthropogenic greenhouse gases being emitted to the environment by disseminating environmental norms. Consistent with this reasoning, they have shown that from the middle of the last century up through the mid‐1990s, nations with more memberships in NGOs have tended to have lower carbon dioxide (CO2) emissions in the aggregate. Doubts remain, however, about whether NGOs have reduced emissions in the time since and at the level of individual power plants where the lion's share of carbon pollution is emitted. Using plant‐specific information on CO2 emissions recently collected by the Environmental Protection Agency (EPA) under its Greenhouse Gas Reporting Program, we investigate the effects of local environmental NGOs (ENGOs) on plants’ environmental performance. Consistent with our expectations, we find that local ENGOs not only directly reduce plants’ emissions but indirectly do so by enhancing the effectiveness of subnational climate policies that encourage energy efficiency. We discuss the implications of our findings for research on the decoupling of normative systems, social movements, environmental sociology, and the EPA's proposed Clean Power Plan.