How does owner identity affect environmental management system (EMS) adoption by business group affiliates? While current research on EMS adoption is mostly focused on stand-alone Western firms, a marked uptake of adoption has unfolded in Eastern countries such as China, where business group affiliates are the dominant organizational form. This stark contrast between corporate interest and research attention has left a clear lacuna in our understanding of how systems that can reduce environmental impact diffuse across industrial settings. We argue that state, family, and foreign owners of affiliated firms show distinct propensities to adopt an EMS, owing to differences in legitimacy needs, ownership competencies, and group-level preferences to engage in systematic environmental practices. Logistic regressions based on data from listed Chinese business group affiliates between 2008 and 2019 show that state and family ownership negatively influence the likelihood of EMS adoption, whereas foreign control has a positive effect. More intragroup transactions exacerbate the low adoption propensity of family-owned firms. Our study contributes to the literatures on business groups and corporate environmentalism.