In my dissertation I address the social, intellectual, and institutional history of the Maḥmūdīyah Madrasa Library, constructed in Cairo, Egypt in the year 797 A.H./1394-1395 CE. According to the contemporary literary sources, the Maḥmūdīyah was the largest madrasa library in Mamluk Egypt and Syria and attracted some of the prominent scholars of the time with its rare and impressive collection of books. In this study I read these literary sources against documentary data that can be gleaned from the Maḥmūdīyah’s surviving manuscripts, which I have identified in modern manuscript libraries around the world. In Chapter 1, I give an overview of modern studies on pre-modern libraries in the Islamic world. I then introduce the methodological and theoretical foundations of my study of the Maḥmūdīyah, namely, the ways in which I make use of manuscript paratexts to reconstruct reading communities and book circulation histories. I also provide the methods I used to locate the manuscripts and book titles that were originally endowed to the Maḥmūdīyah. Chapter 2 traces the provenance of the Maḥmūdīyah’s books to the personal collection of the Grand Shāfiʿī Judge of Egypt, Burhān al-Dīn Ibrāhīm ibn Jamāʿah (d. 790/1388). These books were subsequently seized from the estate of the judge’s son by the emir Jamāl al-Dīn Maḥmūd al-Ustādār, the founder of the Maḥmūdīyah. Looking at the biography of this judge, the textual profile of the Maḥmūdīyah Library from surviving evidence, and the figures who feature prominently on the earlier notes on the Maḥmūdīyah’s books, I argue that Ibrāhīm ibn Jamāʿah had partially aimed to document Syrian hadith and historiographical scholarship through his personal book collection. Chapter 3 looks at the circumstances behind the founding of the Maḥmūdīyah Madrasa in Cairo. I argue that the founder of the library, Maḥmūd al-Ustādār, had created this book endowment as part of a series of measures he took to secure his possessions and wealth from confiscation by the authorities. This chapter also reconstructs the original endowment stipulations and staff positions for the Maḥmūdīyah Madrasa and its library that Maḥmūd al-Ustādār had outlined in his now-lost endowment deed. Chapter 4 turns to the administrative history of the Maḥmūdīyah Library from its founding until its dissolution several centuries later. The clientele and the staff of the Maḥmūdīyah frequently violated the stringent rules concerning hiring practices and the use of the library. Through surviving manuscript evidence this chapter also analyzes that this library was plundered following the Ottoman conquest of Egypt in 923/1517. Finally, in Chapter 5, I analyze the notes left on the Maḥmūdīyah’s manuscripts in order to reconstruct the library’s clientele and their habits of engaging with its books. The results suggest that the textual practice of recording group readings of texts started to decline in the ninth/fifteenth century, and that these practices were replaced by more individual ways of reading. This study is a contribution to Islamic intellectual history, religious endowment history, and manuscript culture in the late medieval Islamic world.