(ProQuest: ... denotes non-USASCII text omitted)Social exchange theory explains how a party in social interaction provides the other party with reciprocal rewards. Applying this concept to the customer context, this study empirically investigates determinants of customer citizenship behaviors (CCBs) in services. For the generalizability of the study across various service providers, the data were collected based on Bowen's (1990) classifications of services. With a total of 665 usable customer responses, structural equation modeling was adapted to test the theoretical research model. This study reveals that customers' perceived support and justice from the service provider positively influence affective commitment toward the organization, resulting in CCBs. The results show that customers' perception of organizational support has the partial mediation effect between customers' perception of organizational justice and their affective commitment. Furthermore, customers' affective commitment partially mediates the relationship between customers' perceived organizational justice and CCBs, but fully mediates the effect of customers' perceived organizational support on CCBs.