This book presents an accessible overview of the seven key concepts of city diplomacy (development cooperation, peacekeeping, economy, innovation, environment, culture, and migration). The book discusses its scope and challenges, maps the actors involved along with their interaction and offers suggestions for available tools and outcomes. Each chapter includes an analysis of a selection of best practices.  The book successfully combines theory with practical evidence and will be an invaluable reference for students and researchers of international relations and urban studies looking for a comprehensive and updated analysis of the multifaceted international action of cities. The book will also be of interest to practitioners and city officials responsible for the design and implementation of impactful diplomatic strategies.