IS projects have been extensively studied, yet continue to be riddled with problems. The concern is aggravated in collaborative IS projects since they involve dual challenges of managing interorganizational relationships and of integrating diverse knowledge bases across organizations that may possess distinct strategic goals and conflicting interests. Prior research has indicated that social capital, a resource based on social relationships, positively influences inter-organizational relationships and knowledge integration. The aim of this study is therefore to identify the roles through which social capital can be leveraged to manage collaborative IS projects, viewing them from an inter-organizational and knowledge integration perspective. Using the case-research strategy and an interpretive approach, a four-organization (three clients and one IT service provider) collaborative IS project is studied. The three clients were business partners for seven years when they embarked on the collaborative project. The study finds that social capital can be leveraged as a Motivator, Integrator and Facilitator; during the various stages of a collaborative IS project. In doing so, the study informs IS projects through two new perspectives (knowledge integration and interorganizational relationships) and by leveraging a resource that inherently emerges in a structure (e.g. collaborative project) due to the opportunity, motivation and ability (OMA) of participating organizations.