Prompted by recent events in the EU's international environmental cooperation, this thought-provoking book explores the establishment and use of multilateral environmental compliance mechanisms as part of the EU's external environmental action. Expanding upon current discussions in external relations law, this timely book uses a doctrinal approach to analyse EU engagement with a key instrument of international environmental governance. The author examines the role of compliance mechanisms in EU environmental action, from establishing these treaty-based mechanisms within EU legal boundaries, to utilising non-compliance decisions at EU level. The book concludes with an evaluation of the extent to which EU law enables the EU to preserve, protect, and improve the global environment with the aid of compliance mechanisms, as required by its own Treaties. Multilateral Compliance Mechanisms in EU Environmental Law will be an essential resource for scholars in environmental law, European law, international relations, and public international law. It will also be beneficial for EU officials and policymakers, and environmental advocates and campaigners.