Islamic religious genres are major elements of Muslim civilization past and present.  To date, our understanding of the formation of religious genres in Islam have relied solely on later literary sources.  But what does the history of Islam's formation look like if told from a perspective that privileges documentary data: The paratextual material in Islamic manuscripts discovered during the last two decades?  This talk focuses on these manuscripts and, in particular the paratexts (marginal notes by scribes and readers and similar data) and their function in the formation, transformation, and development of Islam's religious genres.