This is the first book to explore ancient Greek alliances in terms of both crisis and resilience, offering readers a deeper understanding of how such alliances were formed, dissolved and re-established. The chapters in this volume understand disputes between Greek allies not simply as precursors to alliance breakdown, but as a structural feature of bilateral and federal formations. By analysing their susceptibility to crises from both external (etic) and internal (emic) perspectives, this volume explores how these challenges proved to be catalysts for the transformation and adaptation of alliances. Ancient concepts of crisis were seen as inherent to the system, rather than modern notions of crisis as catalysts for revolution and instability, making resilience and adaptation crucial to the formation of alliances in ancient Greece. The book highlights the creative power and potential of ancient Greek alliances through a range of case studies, which revolve around sections on concepts and historiography, rituals and media, border management and a comparison between the Delian League and NATO. To showcase how the alliances thrived in the face of crises, the views of historiographers like Herodotus, Thucydides and Polybius are discussed. Equally, the actors within alliances are characterised: the Delphic Amphiktyony, powerful poleis like Athens and Sparta and federal states like the Aitolians and the Boiotians. Mainly with a view to Hellenistic kings, the impact of external powers on the texture of Greek alliances also comes into play. Crisis and Resilience in Ancient Greek Alliances will be valuable for students and scholars working on politics and diplomacy in ancient Greece, as well as those interested in ancient history and politics in the ancient world more broadly.