The sheer complexity of sustainability transitions makes it vital to develop simplifying conceptual frameworks. Starting from the contrast between the mainstream innovation-economics and systems-innovation/evolutionary literatures, this paper begins by summarising the “Three Domains” framework, which relates technology innovation and adoption choices to different domains of socio-economic decision-making, at successively larger scales of time and social structures. We note the high-level implications for policy mixes and illustrate the main themes through three electricity technology examples (lighting, fossil fuel generation, and low carbon power systems), and use these also to show that the relative importance of different policy pillars may differ substantially according to the technology and context. We then relate this to the “innovation chain” (another simplifying framework) approach to vertical innovation and show how this can help to explain radical differences in innovation intensities between different sectors. We then expand the innovation chain framework from technology to the multiple journeys required for successful innovation, ordered according to levels of decision-making and hence domains. We conclude by indicating how this can help identify key blockages in energy transformations, and potentially help to reconcile the classical innovation-economics with systems innovation/evolutionary perspectives, and explain their currently divergent policy recommendations.