International Organizations Count

<jats:p> This special issue seeks to move forward the development of an empirical research agenda that takes seriously the complexity of how international organizations (IOs) function and the need to study that complexity at all levels of analysis by using robust research tools. We advocate for a broad empirical research approach that molds and sharpens theories about IOs by conducting systematic tests in large-sample environments. Two themes create a common thread throughout this issue. First, shifting the focus from whether IOs matter to how they work requires acknowledgment of the contingency of cause and effect. A second common thread lies in the authors' treatment of IO membership as an aggregate phenomenon—that is, as a set of institutions and relationships evolving over time and with many members rather than as a single organization. </jats:p>