This chapter presents the central element of an accountability analysis approach-a typology of four practices of legitimation: discursive, bureaucratic, technocratic and financial. These are empirically derived and defined in generic terms as social relations premised on accountability. Their study can characterise accountability under energy transitions. Discursive legitimation practices normalise certain perspectives over others through textual and spoken interventions across a variety of forums. Bureaucratic legitimation practices, often codified and sequential, validate some actions and actors and constrain others. Technocratic legitimation practices perform systematic checks and approval of actions that entail technical expertise. Financial legitimation practices, often spatially remote and materially elusive, enable actors to block action or to fulfil financial requirements and proceed with material actions, shaping sectoral change.