This volume analyses the European Union as an international actor, focusing on its role in peace and security. In an international context where the challenges to peace and security are diverse, including the current context of war in Ukraine, this volume theoretically contextualizes the EU in peace and security studies, explores the institutional dimension of its functioning, and interprets the narratives and policies this actor pursues. A set of illustrative case studies seeks to reflect on the dynamics of peace and security within the framework of the EU and its actions/interventions, such as in the Eastern Partnership or in relations with Russia, and in contexts such as growing disinformation or through its presence on a mission on the ground.