LAUSR

Abstract It is widely assumed that the fragmentation of global governance can affect coordination efforts among international institutions and organisations. Yet, the precise relationship between the fragmentation of global governance and the extent to which international organisations coordinate their activities remains underexplored. In this article, we offer new empirical evidence derived from the so‐called custodianship arrangements in which numerous international organisations have been mandated to coordinate data collection and reporting for 231 indicators of the 17 Sustainable Development Goals (SDGs). These complex custodianship arrangements provide a fertile testing ground for theories on the relationship between fragmentation and coordination because the institutional arrangements for each of the 17 SDGs have emerged bottom–up with varying degrees of fragmentation. Through a comparative approach covering 44 custodian agencies and focusing on the most and least fragmented custodianship arrangements, we make three key contributions. First, we offer a novel operationalisation of institutional fragmentation and coordination. Second, we present empirical evidence in support of the claim that fragmentation negatively affects coordination. Third, we provide nuances to this claim by identifying factors that affect the strength of this relationship. Based on our analysis, we suggest further steps that might facilitate coordination in global sustainability governance.