The Safaviyya sufi order completed its crystallization from a mystical group into a religio-political movement under the banner of the Safavid state at the turn of the sixteenth century. Under the leadership of Sheikh Haydar (d. 1488), the group developed a distinctive identifier in the form of a twelve-gored crimson headpiece symbolizing the adherents’ allegiance to the Twelve Shi‘ite Imams and to the Safavid sheikhs/shahs as their spiritual leaders. This twelve-folded piece of felt, or kızıl taj/tac, gradually became a source of pride and honor, as well as a mark of religious and political loyalty among the followers and sympathizers of the Safavid movement, called Kızılbaş, most of whom were inhabitants of Ottoman Anatolia. Conventional Ottomanist scholarship has defined “Kızılbaş” within a narrow ethno-religious framework, according to which one inherited his/her Kızılbaş identity, often against his/her will. This position reflects the fact that the early modern Ottoman legal establishment assumed that each Kızılbaş mentioned in official Ottoman sources was a “heretic” and thus rationalized persecution of the empire’s largest Muslim minority. This study argues that Ottoman sources use the term “Kızılbaş” in a far more nuanced and varied fashion. For instance, while the term was used rather literally up until the late fifteenth-early sixteenth centuries, later Ottoman sources made a clear distinction between Kızılbaş-born subjects of the empire, Kızılbaş converts, and the Kızılbaş subjects of the Safavid Empire. In the following centuries, the term acquired different symbolic, geographical, and political meanings, reflecting the Ottoman central authority’s relationship with the Safavid polity and/or the issues of taxation and migration. By the nineteenth century, it had become a derogatory term for the Turkish/Kurdish-speaking Shi‘ite community in Ottoman Anatolia. For this study, I examine Ottoman Turkish government decrees, Muslim law court registers, and court chronicles produced between the 1480s and the 1750s, taking account of their rhetorical qualities and the contexts in which they were produced. Exploring these often-neglected variances in the meaning of the term “Kızılbaş” reveals that fluid cultural, religious, regional, and political identities were attached to the term in the early modern era. Awareness of this reality is essential to understanding the Ottoman state’s relationship to a key group of its subjects, and the broader question of the formation of religio-political identities and loyalties in the early modern era.