According to social exchange theory, the motivation for organizational citizenship behavior can be understood with the help of the frameworks of obligation to reciprocate and expected reciprocity. This study predicts that the true motivation for organizational citizenship behavior could be differentiated conditional on the career plateau. These relationships predict the existence of a U-shaped nonlinear relationship between the career plateau and organizational citizenship behavior. In addition to exploring this relationship, the study attempted to discover the effect of organizational commitment and job involvement on the relationship. As a result, a U-shaped curvilinear relationship is applied between career plateau and four dimensions of organizational citizenship behavior except civic virtue. Commitment and involvement show unexpected moderating effects on those curved relationships.