The fact that Oman was never fully isolated from the rest of the Islamic world meant that Omani Ibadis sometimes found it expedient to formulate statements of identity that reified their own sense of what it meant to be Ibadi in relation to other non-Ibadi groups of Muslims. This was done, as it was in Sunni and Shi’ite intellectual spheres, using the medium of heresiography. Abu ‘Abdullah Muhammad b. Sa’id al-Qalhati – an Omani heresiographer and historian from the late 6th/12th, early 7th/13th century – penned one of the most important medieval works of Ibadi heresiography. His Kitab al-Kashf wa’l-Bayan fi Sharh Iftiraq al-Firaq wa’l-Adyan is a work of two parts that first presents early Islamic history, especially the rise of the Ibadiyya in relation to the Kharijites, and then treats the Ibadiyya as part of the constellation of Islamic groups using the standard 72 erring sects format. This paper examines the heresiographical portions of al-Qalhati’s work to determine how, and in what fashion, al-Qalhati creates a notion of Ibadi identity using the medium of heresiography. It will focus on al-Qalhati’s fiftieth chapter in which he mentions the ahl al-istiqama (i.e. Ibadiyya) and elucidates their creed (i‘tiqad). In this chapter, al-Qalhati provides an exposition of Ibadi belief, ritual worship and proper practice that is sandwiched in-between two lists of important personages who transmitted this material, and from whom the Ibadiyya trace their lineage. The paper argues that these genealogies of religion were as important to al-Qalhati and the medieval Ibadiyya as the description of the distinctive Ibadi doctrines and rituals. This emphasis on transmission via teacher lines can likewise be detected in earlier Ibadi writings, just as it can be seen operating in medieval Ibadi attitudes toward hadith. These genealogies have generally been ignored by Western scholars. An examination of how and why al-Qalhati crafted his chapter on the Ibadiyya in the particular in which he did will illuminate novel methods by which scholars can appreciate the process of sect-identity formation.