Climate change is a politically difficult issue, involving short-term costs, relatively distant and uncertain benefits, trade-offs with longer-established policy goals and coordination problems. National governments have failed to produce policy responses commensurate with the challenge with which they are confronted. In established democracies, this is at least partly due to policy positions adopted by political parties. This paper compares the climate policies of six parties in the UK, Italy and Denmark from the late 1990s until the present. Drawing on a systematic comparison of parties’ climate policies, case study research and interviews with key individuals, it aims to explain variation in these parties' climate policies and to identify constraints on policy development. It does so with reference to these parties’ office-, vote- and cohesion-seeking behaviour. It promises to offer new insights into the party politics of climate change and the capacity of democratically elected governments to make effective climate policy.