Coordination within the cluster of organizations formed in the aftermaths of a disaster has been recognized as both a success factor and a key hurdle. In the aftermaths of a disaster a multitude of organizations form a cluster in which they need to coordinate activities and resources to avoid duplication of efforts and to increase relief performance outcomes. Resource sharing is a key aspect of coordination. However, there is little empirical research showing how important resource sharing is for performance benefits and what impacts organization's willingness to share more resources. In this paper, we aim to empirically test the association between resource sharing, aspects impacting resource sharing, and relief performance outcomes. Drawing on the antecedents of resource dependence theory, humanitarian logistics and supply chain management literature was reviewed to explain the extent of relationship between the constructs. 101 data points were collected from the humanitarian agencies within the Southeast Asian region and analyzed using Partial Least Square (PLS) path modeling. Results show that contrary to the commercial sector where the impact of interdependence of organizations on performance is apparent, in the humanitarian context it is mediated by resource sharing. Complementarity of resources between organizations was found to have a significant impact on resource sharing. Finally, flexibility was considered less important in defining relief performance for the humanitarian agencies.