Chapter 1 elaborates on how the assemblage of multilateral, bilateral, transnational, and private nongovernmental actors – the clean energy regime complex – interacts with domestic politics in emerging economies and developing countries (EMDEs) to foster energy transitions. The ripple effects of international norms regarding energy transitions are visible in domestic institutional change in Indonesia and the Philippines, but both cases demonstrate variable outcomes in terms of the relative impacts of the clean energy regime complex in removing barriers to geothermal development. The chapter underlines the importance of studying the interaction between the international and domestic politics in EMDEs to understand how best to catalyze energy transitions to meet global climate mitigation goals. The chapter summarizes the case study selection, research design and methods, and theoretical arguments on regime complex effectiveness mechanisms – including utility modifier, social learning, and capacity building, and their impact in overcoming domestic political lock-in. The chapter also provides a brief overview of the book.