Concerns about energy transition and policies to achieve a clean energy Europe are omnipresent in all European discourses. A transformation dynamic has captured all European states, whereby the extent, scope, and direction of this transition vary between different (EU member‑) states and political levels (European, national, federal, local). Likewise, governance dynamics and policies vary between the different European governance and regulatory systems. This Special Issue aims to take stock and discuss approaches in governance and policy research to assess, analyse and evaluate this variance from a theoretical, methodological, and empirical perspective. Of particular interest are recourses to investigate concepts describing and analysing the formation of new policy fields. Within the framework of the Special Issue, the role of specific architectures in which the energy transformation in Europe is embedded (e.g., federalism and multi-level structures, institutional constellations of actors, multi-sector networks, etc.) are analysed to explain the energy transition policies and their transformative properties. Linking the empirical results back to basic research concepts and relating the results to the existing approaches in policy and governance research facilitates a better understanding of the energy transition as a classic and/or new transformation policy.