This paper contributes to understanding transition politics by conceptualizing (shifting) power relations between actors in sustainability transitions. The authors introduce a Multi-actor Perspective as a heuristic framework for specifying (shifting) power relations between different categories of actors at different levels of aggregation. First, an overview is provided of how power and empowerment have been treated in transition research, and remaining questions are identified on who exercises power and who is empowered by and with whom. It is argued that theoretical frameworks and empirical analyses in transition studies lack precision when it comes to distinguishing between different types and levels of actors. In response, a Multi-actor Perspective (MaP) is developed, which distinguishes among four sectors (state, market, community, third sector), and between actors at different levels of aggregation: (1) sectors, (2) organizational actors, and (3) individual actors. The paper moves on to specify how the MaP contributes to understanding transition politics specifically in conceptualizing shifting power relations. Throughout the paper, empirical illustrations are used regarding public debates on welfare state reform, civil society and ‘Big Society’, as well as more specific empirical examples of community energy initiatives.