Highly topical work raising uncomfortable questions about power, inequality, inclusion, representation and linguistic justice in contemporary global deaf spaces International Sign (IS) is widely relied upon as a lingua franca of sign languages in international contexts, yet it remains one of the most debated and misunderstood forms of signed communication. Through extensive multinational ethnographic fieldwork, this book explores the paradox of IS: it often works best when it remains open and fluid, yet it becomes visible, teachable, interpretable and institutionally useful only through processes that seek to define it. Foregrounding deaf perspectives on language use, the book examines key dynamics of IS and traces how these are organised, evaluated and contested across informal and institutional settings. It includes visual vignettes, single-sign illustrations and links to ethnographic films created by the author allowing readers to engage with multimodal data in context and providing material for teaching and further research. This book will be of particular interest to researchers and students in sign linguistics, deaf studies, interpreting studies, sociolinguistics and linguistic anthropology as well as professionals working in deaf organisations, sign language interpreting, policy and media contexts. This book is open access under a CC BY NC ND licence.