Authors such as Dryzek, Gough and Meadowcroft have indicated that social-democratic welfare states could be in a better position to deal with development of the ‘green’ or ‘eco’ state, and the intersection of social and environmental policies, than conservative or liberal welfare regimes (synergy hypothesis). However, this hypothesis has as yet not been examined in comparative empirical research. Based on comparative empirical data from EUROSTAT, the World Bank, the OECD, the Global Footprint Network and the International Social Survey Programme, we are carrying out two research operations: First, by applying correspondence analysis, we contrast the macro-structural welfare and sustainability indicators of thirty countries and ask whether clusters largely follow the synergy hypothesis. Second, we raise the issue of whether differences in the institutional and organisational capabilities of combining welfare with environmental policies are reflected in people's attitudes and opinions. With regard to the first issue, our results suggest that there is no ‘automatic’ development of the ecostate based on already existing advanced welfare institutions. Representatives of all welfare regimes are spread across established, deadlocked, failing, emerging and endangered ecostates. As for the second issue, the results are mixed. While responses to the statements ‘economic growth always harms the environment’ and ‘governments should pass laws to make ordinary people protect the environment, even if it interferes with people's rights to make their own decisions’ did not vary according to welfare regimes, people from social-democratic countries expressed more often than average their willingness to accept cuts in their standard of living in order to protect the environment.