The scope of this project revolves around a close study of the Dīrghāgama manuscript (The Collection of Long Discourses), an important collection of Buddhist sūtras detailing the discourses of the historical figure known as the Buddha Gautama. This manuscript is the only surviving witness of this textual collection as it was transmitted by the Mūlasarvāstivāda Buddhist tradition, one of the three major Buddhist traditions from which the entirety of the religion as it is practiced today is descended. The project will examine the Dīrghāgama manuscript holistically, laying out a detailed analysis of it as both a physical object and as a text containing important works of Buddhist religious doctrine. To this end, a detailed study of the codicological and paleographical aspects of the manuscript will be undertaken that will answer questions surrounding its creation by a group of scribes in a scriptorium in the area of Gilgit (the modern day border area of Pakistan and Afghanistan) and the relationship between this scriptorium and other texts found in the area, as well as a comparative study of the content of the manuscript that will untangle intricate intertextual relationships found between this text and its extant parallels: the Theravāda Dīghanikāya surviving in Pali, and the Dharmaguptaka Cháng āhán jīng 長阿含經)in Chinese. This research will ultimately result in new understandings of the authorship, creation, and development of major Buddhist textual traditions.