This study examines opportunities for and obstacles to the mitigation of climate change in US cities using the example of the Cities for Climate Protection (CCP) campaign sponsored by the International Council for Local Environmental Initiatives. The CCP experience suggests a number of ways in which municipal governments can control greenhouse gas (GHG) emissions but also highlights several obstacles that make it difficult for local officials to do so. First, climate change is generally framed as a global issue. The CCP experience suggests that climate change is most likely to be reframed as a local issue when the preferred policy response (controlling GHG emissions) can be linked to issues (e.g. air quality) already on the local agenda. Secondly, even when local governments recognise that they should do something to control GHG emissions, institutional barriers make it difficult for municipalities to move from political rhetoric to policy action. Finally, it is questionable whether local initiatives can make meaningful contributions to climate change mitigation in the absence of policy changes at the state and national levels.