Environmental impact assessment (EIA) has become one of the most widespread environmental management instruments. Despite this, EIA is routinely criticized for being ineffective at impacting decision-making. This study compared the EIA systems of Paraná, Brazil and California, United States using the effectiveness dimensions from the EIA literature. This study formats the cases into contextual conditions using the fuzzy-set qualitative comparative analysis (fsQCA) to identify the necessary or sufficient conditions that cause effective outcomes. These effectiveness outcomes are then ranked by EIA stakeholders via the analytical hierarchy process (AHP) to identify stakeholder priorities and to improve stakeholder management. The results show that in Paraná stakeholders identified normative effectiveness as the most important dimension, while stakeholders in California identified this dimension as the second-most important following substantive effectiveness. Public participation was found to be a necessary condition for both substantive and normative effectiveness to occur. Early project definition was found to be sufficient for substantive effectiveness and necessary for normative effectiveness, for which stakeholder coordination was a sufficient condition. This suggests that in order for EIA to influence decision-making and foster sustainable development, greater care needs to be taken to actively engage stakeholders in public participation, with clear roles and project design communicated early on, and a clear role for regulatory authority to promote stakeholder coordination for acceptable outcomes. These findings suggest that some effectiveness dimensions are caused by similar conditions, which could help focus stakeholder management efforts and point to new avenues for future EIA effectiveness research.

环境影响评估（EIA）已成为最广泛使用的环境管理工具之一。尽管如此，环境影响评估仍经常因在影响决策方面无效而受到批评。本研究使用 EIA 文献中的有效性维度比较了巴西巴拉那州和美国加利福尼亚州的 EIA 系统。本研究使用模糊集定性比较分析 (fsQCA) 将案例格式化为情境条件，以确定产生有效结果的必要或充分条件。然后，EIA 利益相关者通过层次分析法 (AHP) 对这些有效性结果进行排名，以确定利益相关者的优先事项并改进利益相关者管理。结果表明，巴拉那州的利益相关者认为规范有效性是最重要的维度，而加利福尼亚州的利益相关者则认为该维度是继实质性有效性之后第二重要的维度。公众参与被认为是实质性和规范性有效性发生的必要条件。人们发现，早期的项目定义足以实现实质性有效性，并且对于规范性有效性也是必要的，而利益相关者协调是其充分条件。这表明，环评要影响决策、促进可持续发展，需要更加注重利益相关者积极参与公众参与，尽早沟通明确的角色和项目设计，监管部门明确角色以促进可持续发展。协调利益相关者以获得可接受的结果。这些发现表明，某些有效性维度是由相似的条件引起的，这可能有助于集中利益相关者的管理工作，并为未来 EIA 有效性研究指明新途径。