This article provides directions for advancing the conceptualization of the relationship between social movements and institutionalization, based on a case study of the Swedish environmental movement strategies. We argue that the concepts of (de) responsibilization and (de) politicization provide tools for an improved analysis of the dynamics of how social movements interact both with established political institutions and corporations in a new context. The introduction of new regulatory frameworks in environmental politics has shaped interaction between social movements and the state in new ways, involving neoliberal responsibilization, meaning active involvement by civil society and business in political responsibilities previously associated with state agencies - a development involving an increasing emphasis on market mechanisms. We argue that this has involved a de-politicization of environmental issues in the sense that it engages political actors in a moral discourse and a technocratic practice that suppresses the (potential) articulation of social conflict through consensus building. However, we also show how movement actors resist the discourse that encourages them to take on certain responsibilities, thus engaging in a politics of responsibility. Empirically, we demonstrate how the changing strategies of the Swedish environmental movement in the 2000s need to be understood in relation to the following processes, indicating that the Swedish case has a general relevance for an understanding of the contemporary environmental movement globally: (1) the transformation of the Swedish model of welfare capitalism under the influence of neoliberal discourse; (2) international environmental policy developments, most importantly the emergence of climate change as a dominant issue globally.