Drawing on Bansal & Roth's model of ecological responsiveness, the study investigates how environmental managers' cognitive framings of sustainability issues and interpretations of field-level contextual factors affect decision-making processes with regard to environmental management system (EMS) internalization. Using data from a survey questionnaire of 457 ISO 14001-certified and EMAS-registered European companies, the research analyses the influence of managers' perceptions of contextual factors (i.e. environmental issue salience and governmental regulatory incentives) and managers' cognitive traits (i.e. managers' environmental concern and cognitive framings of environmental practices) on internalization. The results highlight that, while managers' perceived stakeholders' concern for the natural environment directly influences substantive internalization, governmental regulatory reliefs fail to influence the internalization of EMS. Similarly, managers' environmental concern emerges as an antecedent of internalization, while managers' adherence to an alignment logic between economic and environmental objectives does not contribute to internalization. Furthermore, the study contributes to the conceptualization of substantive internalization of environmental practices, by highlighting the existence of two distinct dimensions of EMS internalization, i.e. operational and strategic internalization. •The paper explores antecedents of environmental management systems (EMS) internalization related to managerial interpretations of contextual factors and managers' cognitive traits.•The study analysis data from a survey of 457 ISO 14001-certified and EMAS-registered European companies in different sectors.•The results highlight that environmental issues salience influences EMS internalization, while governmental regulatory reliefs do not.•Managers' environmental concern emerges as an antecedent of internalization, while managers' adherence to an alignment logic between economic and environmental objectives does not influence internalization.•The study advances the understanding of EMS internalization in terms of operational and strategic internalization.