Only rarely have empirical studies analysed the responses of Taiwanese manufacturing firms to ISO 14001, despite firm responses to environmental issues being an important aspect of environmental management. This study empirically examines the determinants of firms’ environmental self-governance. Export oriented Taiwanese firms, which face environmental concerns from foreign consumers, are found to be more likely than domestic focused firms to adopt ISO 14001. This study also finds that several firm attributes are decisive for firm adoption of ISO 14001. However, this study does not find any significant impact of local governors’ political party affiliation on firms’ ISO 14001 certifications.