While many have observed a regime complex for global clean energy governance, research has not yet accorded sufficient attention to the interplay of multiple streams of politics that have led to the structuring of overlapping governance initiatives and, ultimately, the articulation of a set of norms that hold this regime complex together. To understand these dynamics, this article argues that with the visibly increased agency of transnational actors and international organizations, four mechanisms together are likely to shape regime complexity: divergent state preferences, the agency of transnational actors, practices of intergovernmental organizations, and interorganizational recognition and normative legitimation. Drawing on a qualitative analysis of policy documents and interviews, and a social network analysis, it studies global clean energy governance from 1980 to 2014 to illuminate these dynamics. The findings suggest that the combination of these four mechanisms can explain the evolution from a nonregime to a loosely coupled governance system for clean energy.