International organizations (IOs) operate in increasingly dense institutional networks. This means that IOs rarely act in isolation; instead, their decisions are shaped by the activities performed by other IOs in their issue area. However, existing literature focuses primarily on how individual IOs can solve cooperation problems in a vacuum. How and when can IOs broadly, and U.S.-led liberal IOs in particular, effectively pursue their mandates against the backdrop of institutional crowding? In a three-paper dissertation, I probe the evolution of multilateral cooperation networks and how they structure policymaking in liberal IOs. To explore these dynamics, I construct an extensive, hand-coded dataset of cooperation between organizations in the development and emergency lending issue spaces 1945-2018. This coding draws on the contents of thousands of organizational policy papers, program documents, and press releases. I then leverage quantitative methods, text analysis, and network modeling to analyze these data.

I supplement the empirical results with semi-structured interviews and experimental research designs. While existing work suggests that IOs must make concessions to member states to prevent them from shopping between institutions or else restrict their mandates to reclaim monopoly authority, I show that IOs can achieve their mandates and combat complexity through cooperation. In the first paper, I show that such cooperation materializes most easily between IOs whose leading stakeholders are geopolitically aligned. This is because multilateral staff are selected and socialized by leading shareholders to hold beliefs similar to their own. In the second and third papers, I show how cooperation enables IOs to enforce more stringent policies and improve operational performance. On the whole, then, I show that U.S.-led IOs like the World Bank and IMF can coerce welfare-enhancing reforms in target states and promote good governance by cooperating with other organizations in their issue spaces, though geopolitical tensions between the U.S. and other leading IO member states may be obstructive.