This book, by a group of leading international scholars, outlines the history of the spoken dialects of Arabic from the Arab Conquests of the seventh century up to the present day. It specifically investigates the evolution of Arabic as a spoken language, in contrast to the many existing studies that focus on written Classical or Modern Standard Arabic. The volume begins with a discursive introduction that deals with important issues in the general scholarly context, including the indigenous myth and probable reality of the history of Arabic; Arabic dialect geography and typology; types of internally and externally motivated linguistic change; social indexicalisation; and pidginization and creolization in Arabic-speaking communities. Most chapters then focus on developments in a specific region - Mauritania, the Maghreb, Egypt, the Levant, the Northern Fertile Crescent, the Gulf, and South Arabia - with one exploring Judaeo-Arabic, a group of varieties historically spread over a wider area. The remaining two chapters in the volume examine individual linguistic features of particular historical interest and controversy, specifically the origin and evolution of the b- verbal prefix, and the adnominal linker -an/-in. The volume will be of interest to scholars and students of the linguistic and social history of Arabic as well as to comparative linguists interested in topics such as linguistic typology and language change.