The decreasing importance of the state as a prominent actor in international politics has opened a debate about the rising importance of transnational relations. The research focuses on other actors, including epistemic communities. The paper traces previous research using the concept of epistemic communities and their influence in international politics and responds to its limitations. It uses the social constructivist approach for the elaboration of criteria of the professionalization process needed for recognition of epistemic communities. The paper also elaborates the concept of their influence in international regulation, including defining conditions of demand for epistemic communities’ activities. The conditions include the introduction of complex problems with an element of uncertainty, acquisition of direct or indirect access to the political decision-making process in the arenas of international politics, and the ability of these arenas to execute international regulation. The paper also explains and elaborates the diffusion process of shared beliefs created by epistemic communities. The ability to diffuse shared beliefs supports modes of persuasion including statistical indicators, focusing events and narratives. Shared beliefs transfer via a process of institutional learning. Successful transfer means that shared beliefs become part of a political agenda. Utilization of the shared beliefs for creation, execution and enforcement of political decisions manifests the influence of epistemic communities in international politics.