This study explores the applicability of social capital theory in IT project management. Specifically, an empirical model is developed using different types of leadership competencies (emotional, cognitive, and social) as independent constructs impacting IT project performance. Social capital shared among team members are measured and placed as a mediating construct between leadership competencies and performance. Using PLS analysis of 120 data points collected through a survey of IT project participants in two large electronic manufacturers, direct and indirect impacts of leadership competencies are explicated. Research results reveal that emotional leadership competency seems to directly influence the project performance but not through team social capital, while social leadership competency seems to indirectly influence the project performance through team social capital but not directly onto the project performance. Cognitive leadership competency is the only leadership competency that maintains direct and indirect influence on project performance. Total effect of cognitive competency on project performance is almost two times larger than the total effect of emotional leadership competency and six times larger than the total effect of social leadership competency. Implications of findings are discussed at the end, and further studies are suggested.