A 'Babylonian' variety of policy network concepts and applications can be found in the literature. Neither is there a common understanding of what a policy networks actually is, nor has it been agreed upon whether policy networks constitute a mere metaphor, a method, an analytical tool or a proper theory. The aim of this paper is to review the state of the art in the field of policy networks and to explore their usefulness in studying European policy-making and European governance. It is argued that policy networks are more than an analytical tool box for studying these phenomena. What is so special then about policy networks? They constitute arenas for non-strategic, communicative action providing solutions for collective action problems and accounting for more efficient and legitimate policy-making. Yet, a theoretically ambitious policy network approach has to, first, show that policy networks do not only exist but are relevant for policy process and policy outcome, and second, tackle the problem of the ambiguity of policy networks, which can do both enhance and reduce the efficiency and legitimacy of policy-making.