Humanitarian social enterprises (HSEs) are facing mounting pressure to incorporate social innovation into their practice. This study thus identifies how HSEs leverage organizational capabilities toward developing social innovation. Specifically, it considers how resource scarcity and operating circumstances affect the capabilities used by HSEs for developing social innovation, using a longitudinal case study approach with qualitative data from 12 hunger-relief HSEs operating in the United States. Based on 59 interviews with 31 managers and directors and related documents, several propositions are posited. (...) The findings suggest that resource availability (i.e., scarcity vs. abundance) leads some HSEs to focus on developing social innovation using their collaborative capabilities, while others leverage their absorptive capacity. Further, HSEs adjust their approach to developing social innovation based on whether they are operating in ordinary circumstances (i.e., before the COVID pandemic) or extraordinary ones (i.e., during the COVID pandemic). Interestingly, the findings suggest that the organizational capabilities used by HSEs are adjusted as these enterprises become more familiar with extraordinary operating circumstances. For example, at the onset of the COVID-19 pandemic, resource-scarce HSEs focused on parallel bricolage to develop social innovation. Subsequently, they focused on selective bricolage. The findings offer novel insights by relating the social innovation of social enterprises to crisis management. (shrink)