Climate change adaptation has emerged in the last decade on the policy agendas of national and subnational governments. Public participation is often postulated for policy responses to climate change. But the question of whether participation actually improves policy-making has been insufficiently analysed empirically. Furthermore, climate change adaptation policy has to cope with special challenges like the uncertainty of climate change scenarios, lack of knowledge about climate change impacts at regional and local levels and in different sectors, as well as the long-term nature of the problem. The research project A-CLIM (Analysis of Climate Change Adaptation Strategy Development in Lower Saxony) compares a multi-year participation process in Lower Saxony to processes of strategy making in other federal states, which developed adaptation strategies without involving a wide range of interest groups. A-CLIM is part of KLIFF (Climate Impact and Adaptation Research in Lower Saxony) – a cooperative research initiative of 21 universities and research facilities.