While its importance in domestic law has long been acknowledged, transparency has until now remained largely unexplored in international law. This study of transparency issues in key areas such as international economic law, environmental law, human rights law and humanitarian law brings together new and important insights on this pressing issue. Contributors explore the framing and content of transparency in their respective fields with regard to proceedings, institutions, law-making processes and legal culture, and a selection of cross-cutting essays completes the study by examining transparency in international law-making and adjudication.