The relation between organizational citizenship behavior (OCB) and the performance of both safety and environmental management systems has led researchers to investigate the drivers of safety-specific and environmental-oriented OCB. However, although the management of environmental and safety issues is often fully integrated into organizational and managerial practice, a holistic perspective of the drivers of health, safety, and environmental (HSE)-oriented OCB is still lacking. Thus, the aim of the present study is to investigate the antecedents of HSE-related OCB (OCBHSE).Drawing on both the OCB and sustainability literature, data from 135 managerdirect report dyads collected from eight large Italian companies are analyzed, to assess the effect of both situation-related antecedents (i.e., organizational ambidexterity and leadership style) and person-related antecedents (i.e., prosocial values) on prosocial and proactive OCBHSE. Organizational ambidexterity emerges as a direct situation-related antecedent of both prosocial and proactive OCBHSE, whereas management by exception and passive leadership have a negative effect on the OCBHSE in direct reports. Surprisingly, transformational and contingent reward leadership styles do not emerge as significant drivers of OCBHSE. In terms of person-related antecedents, the results highlight that prosocial values in direct reports significantly influence prosocial but not proactive OCBHSE. Finally, as OCBHSE is conceptualized in the study as a dimension that is complementary to formal HSE management structures, our findings can contribute to the general organizational effort to improve HSE performance.