The review of environmental impact statements (EIS), despite its relevance to impact assessment effectiveness, has received scarce scholarly attention. Few studies have gone beyond the realm of regulatory evaluations to understand the managerial meanders of the review process. This study evaluated the responsibilities, procedures, information inputs, and scope of EIS reviews within two environmental authorities: APA (Portuguese Environment Agency), in Portugal, and SEMAD (State Secretariat for Environment and Sustainable Development), in the Brazilian state of Minas Gerais. Based on a qualitative multiple-case study methodology informed by participant observation, unstructured interviews, and content analysis of 12 EIS review reports, the study provided what is arguably one of the most detailed characterizations of EIS review to date. While following similar institutional arrangements and broad procedural steps, the EIS review has important differences in APA and SEMAD. Overall, the Portuguese agency was found to have a more structured, participative, interdisciplinary, detailed, and grounded review, thus meeting some of the good practices often cited in the literature. The EIS review reports prepared by APA reviewers were also found to provide a profoundly more complete and transparent account of the review process. The details of the review process revealed in the article can affect perceptions around the legitimacy and reliability of reviewers’ recommendations.