The present research aims to explore the direct and indirect influence of passion and empowerment on organizational citizenship behavior of Teachers in Assumption University of Thailand mediated by organizational commitment. The sample comprises of 124 teachers teaching in the University and the Organizational Citizenship Behavior Scale, adapted by Podsakoff and Mackenzie (1990), Passion Scale, developed by Vallerand et al. in 2003, School Participant Empowerment Scale (SPES) developed by Short and Rinehart (1992) and Organizational Commitment Scale which was modified from the original scale of Allen and Meyer (1991) by Meyer, Allen, and Smith (1993) were employed. The path model with the dependent variable organizational citizenship behavior and the independent variables passion, and empowerment and the mediating variable organizational commitment was tested using regression analysis. There are relationships between passion for teaching, teacher empowerment, and organizational commitment on the organizational citizenship behavior of teachers in Assumption University, Thailand. The teachers have high level of organizational citizenship behavior, suggesting that they exhibit behaviors of discretionary nature that are not part of their formal role requirements, but which promote the effective functioning of the University.