This chapter investigates how the International Organization for Migration (IOM) dramatically expanded its involvement in humanitarian emergencies over the past three decades. Building on insights from historical institutionalism in international relations, we hypothesize that crises which touch upon matters of migration may constitute opportunities for IOM to expand the range of its activities as contingencies call for flexible responses that the organization is (the only one) apt to deliver. The 1990-91 Gulf War served as a ‘critical juncture’ in this regard, where IOM started to expand more forcefully into the broad realm of humanitarian assistance. It set a precedent that served as best-practice example and led to an ex post formalization of the institutional expansion through corresponding frameworks for action. As we show in case studies of the 2011 Libyan civil war and the 2014-16 Ebola crisis, this pattern holds across a variety of crisis contexts: humanitarian emergencies expose gaps in the governance architecture that IOM is quick to fill, thereby increasing the range of its activities which is later normalized in institutional rules and practice. Today’s vast array of humanitarian and other crisis-related tasks fulfilled by IOM attest to the lasting ‘power of precedent’.