The inclusion of representational imagery in a sacred context is extremely rare in the history of Islamic art. This dissertation examines the evolution of the Ottoman En'am-i Serif, a group of manuscripts dating from the sixteenth to the nineteenth centuries, in which sacred text was illuminated by sacred art. In the early period, the content of these prayer books consisted of entire chapters of the Qur'an and various prayers. In the seventeenth century, calligraphic images known as hilye were added, consisting of textual descriptions of the Prophet Muhammad's physical and moral characteristics. In the late eighteenth and nineteenth centuries, representational images of the Prophet's mantle, hand, footprint, sandal, sword, and other relics were included for the sake of their baraka, the Divine grace that emanates from God and passes to ordinary people through the prophets and saints, or the objects that they touch. That Ottoman Islam was heavily influenced by Sufism is apparent in the En'am-i Serif. Its calligraphers and patrons were members or affiliates of the various Sufi orders, and they were also frequently highly placed members of the ruling class. At the same time that the Ottomans were defending themselves against the rise of European nationalism, Islam came under attack from within as the Wahhabi movement challenged the Ottoman sultan's role as protector of the holy cities of Mecca and Medina. It is not surprising that Sufi calligraphers chose this precise moment to transform a simple book containing Qur'anic text and prayers into an elaborate manuscript combining sacred text with images of sacred places and objects. In addition to reinforcing the spiritual aspects of Islam that had come under attack from the fundamentalist movement, the artists of the En'am-i Serif also made a strong political statement by choosing to present these images in such a way as to highlight the Ottomans' role as the rightful inheritors of the caliphate and protectors of Islam. / Graduate