The central idea animating environmental impact assessment (EIA) is that decisions affecting the environment should be made through a comprehensive evaluation of predicted impacts. Notwithstanding their evaluative mandate, EIA processes do not impose specific environmental standards, but rely on the creation of open, participatory and information rich decision-making settings to bring about environmentally benign outcomes. In light of this tension between process and substance, Neil Craik assesses whether EIA, as a method of implementing international environmental law, is a sound policy strategy, and how international EIA commitments structure transnational interactions in order to influence decisions affecting the international environment. Through a comprehensive description of international EIA commitments and their implementation with domestic and transnational governance structures, and drawing on specific examples of transnational EIA processes, the author examines how international EIA commitments can facilitate interest coordination, and provide opportunities for persuasion and for the internalisation of international environmental norms.