Orthodox international relations theory considers foreign affairs to be the exclusive purview of national governments. Yet as Rodrigo Tavares demonstrates, the vast majority of leading sub-states and cities are currently practicing foreign affairs, both bilaterally and multilaterally. Subnational governments in Asia, the Americas, Europe and Africa are changing traditional notions of sovereignty, diplomacy, and foreign policy as they carry out diplomatic endeavors and establish transnational networks around areas such as education, healthcare, climate change, waste management, or transportation. In fact, subnational activity and activism in the international arena is growing at a rate that far exceeds that carried out by the traditional representatives of sovereign states.Paradiplomacy is the definitive first practitioner's guide to foreign policy at the subnational level. In this seminal work, Tavares draws from a unique pool of best practices and case studies from all over the world to provide a comprehensive and critical overview of the conceptual, juridical, operational, organizational, governmental and diplomatic parameters of paradiplomacy.