Explores early Ottoman popular piety through the lens of the Yazicioglu brothers • The first book-length study in English on the Yazicioglu brothers, among the most popular vernacular religious writers and thinkers of the early Ottoman period • Reconstructs the Yazicioglus' biographies, assesses the heritage of their language and ideas and analyses the ways these were adapted to their distinct setting • Argues that Ottoman popular orthodoxy emerged as a synthesis of a cosmopolitan Islamic canon to address the needs of Turcophone Muslims of the Ottoman lands • Contributes to the study of non-elite intellectual life of Ottoman Muslims at the dawn of an imperial age. This study follows the lives and ideas of the Yazicioglu brothers Mehmed Yazicioglu and Ahmed Bican, Sufis of the frontier city of Gelibolu and authors of the most popular religious writings in Ottoman Turkish.