A large body of literature in international relations has attempted to explain the interaction between domestic politics and International Relations in the field of trade policy. This article provides new critical insight into the literature on two-level games published during the last 25 years and their contribution to the study of international trade cooperation. I will outline the relevant two-level games literature to establish what we already know about international bargaining and domestic sources of multilateral trade cooperation. I first examine two major perspectives, the domestic political approach and the systemic (international) perspective by presenting a critical review of the literature. I then identify new avenues for theoretical and empirical research in the field. I suggest that to bridge the present rigid division between Comparative Politics and International Relations we need two-level games studies in the following areas: cross-country comparisons on domestic political processes; actor interactions at different levels; comparison of international bargaining processes; and middle-range theory-building.