The Sunnī-Shi'a schism is often framed as a dispute over the identity of the successor to Muhammad. In reality, however, this fracture only materialized a century later in the important southern Iraqi city of Kūfa (present-day Najaf). This book explores the birth and development of Shī'i identity. Through a critical analysis of legal texts, whose provenance has only recently been confirmed, the study shows how the early Shi'a carved out independent religious and social identities through specific ritual practices and within separate sacred spaces. In this way, the book addresses two seminal controversies in the study of early Islam, namely the dating of Kufan Shi'i identity, and the means by which the Shi'a differentiated themselves from mainstream Kufan society. This is an important, original, and path-breaking book that marks a significant development in the study of early Islamic society.