‘Vulnerability’ is increasingly propagated and contested within recent policy frameworks dealing with migration and international protection. In this article we examine how vulnerability as a mobile policy concept becomes embedded in specific sites as it meets institutions, policy frameworks, actors’ strategies and belief systems, and physical–infrastructural characteristics on the ground. To what extent and in which ways is the question of ‘Who gets to be recognized as vulnerable?’ shaped by the shifting assemblages through which the concept travels, and is transformed in different contexts? Based on data from comparative ethnographic studies in six migration arrival hubs, we examine first how vulnerability functions as a governance tool in the reception process. Based on a comparative analysis of how vulnerability is understood and operationalized in and across the sites, we subsequently identify two dimensions that are crucial to shaping vulnerability as governance; the constitution of actor-assemblages identifying and attending to vulnerability in the context of (neo-)liberal marketization, and the ‘nativist’ rhetoric that currently circulates in migration policy and public debate.