Although literature on energy cooperation highlights that cooperation is more successful at the regional level, it largely fails to understand and conceptualize energy cooperation as part of the wider phenomenon of regionalism. Energy cooperation tends to be analyzed through prisms of security and geopolitics, thus, downplaying other important regional integration processes. The present paper addresses this lacuna, defining energy regionalism and conceptualizing its various dimensions, logics, motivations, and interests. We apply a comparative perspective, examining two regions which exhibit extensive energy cooperation yet differ in several ways: North America and the European Energy Community. Our findings suggest various trajectories and models, and indicate that formal institutionalization is neither a necessary condition for nor a guarantee of strong energy regionalism. We discern that regional anchor is key in North American and European energy regionalism.