This report examines the relationship between institutional interplay and the effectiveness of international regimes. It provides an overview of the present literature on regime interplay, arguing that concepts and propositions developed to date fail to relate sufficiently to broader theoretical and substantive knowledge on international institutions. Scholars must be more explicit about whether they address the significance of interplay for regime formation, regime maintenance, or regime effectiveness. This is necessary in order to move forward, because a taxonomy of interplay that works in one of those domains is likely to fail in one of the others.
The effectiveness-oriented taxonomy of interplay proposed here is derived from the general literature on regime effectiveness. It distinguishes between utilitarian, normative, and ideational interplay and highlights the significance of interplay management. By mobilizing findings in the fields of economic institutionalism, international legitimacy, and the study of policy transfer, this taxonomy permits the elaboration of well-based propositions on how regime interplay affects regime effectiveness.