Voluntary cooperation is essential for organizations. Within psychology its explanation is settled in the fields of prosocial behavior and of cooperation in social dilemmas. In addition, this paper draws on another field with strong parallels, namely research on Organizational Citizenship Behavior (OCB) and intertwines these approaches. Following the conceptualization of OCB, the concept of cooperation is to be differentiated and the motivational structures of its proposed facets are to be examined. For that reason a standardized online-questionnaire study was conducted (N=271). Results show that the theoretically proposed differentiation of cooperation at the workplace can be verified empirically. Furthermore, these two facets of cooperation, addressing the social relationship with the colleagues on the one hand and on the other hand the pure thematical context of the organization, are determined by a distinct motivational structure. In line with past work on OCB, job satisfaction turns out to be an important predictor for both facets of cooperation, whereas the assumptions of the cooperative willingness of the colleagues is especially important for the socially intended cooperative behavior. Justice motives on the other hand gain overwhelming significance for cooperative behavior addressing the thematical context. Implications for the theoretical and applied research on cooperation are discussed
