One of entrepreneurs’ key tasks is mobilizing resources from external resource holders. Although we know how entrepreneurial ventures gain initial access to resources, we do not yet fully understand how they maintain their resource mobilization, particularly in the face of potential threats. During our 11-month study of prosocial ventures that emerged to alleviate the suffering of refugees in Germany, four attacks on the European public occurred that were allegedly committed by refugees. These attacks disrupted the German welcoming culture for refugees, potentially threatening the legitimacy of the prosocial ventures’ core activities. Thus, the attacks provide a starting point for examining how new prosocial ventures are able to maintain access to resources in the face of the potential withdrawal of resource holders. Theorizing from our data, we identify three distinct approaches to explain how prosocial ventures responded to the potential threat undermining the legitimacy of their activities to maintain access to resources. These approaches differ in their initial resource mobilization (i.e., based on the venture’s goal for alleviating suffering), threat appraisals, and responses to maintain resource mobilization in the face of the potential delegitimization of their core activities. Our model provides novel insights into resource mobilization and prosocial venturing.