Ad hoc coalitions are an increasingly indispensable, but under-researched and scantly conceptualized part of the increasingly complex global governance architecture. Remarkably, while scholars have spent much effort into providing typologies and classifications of international organizations (e.g. differentiating them on the basis of their membership, geographical scope, tasks, function, centralization, etc.), the label ‘ad hoc coalitions’ is still mainly treated as a catch-all concept missing conceptual precision and a well formulated research agenda. In this paper, we first present a fine-grained conceptualization of ad hoc coalitions, differentiating them from other global governance mechanisms such as, amongst others, international (governmental) organizations, informal organizations and low-cost institutions. This article explores the nature of ad hoc coalitions, providing a definition of the term and developing a comprehensive research agenda. The paper ends with a presentation of initial findings from the first-ever dataset on ad hoc coalitions in global security and health from 2000 onwards. In this way, it intends to inform analysis of the role of ad hoc coalitions in tackling crises in contemporary and future global governance.
