Buddhism is an integral part of the historical development of Khmer society. Though overshadowed during the Angkorian period (9th to 15th c. CE) by the dominant Brahmanical sects of Siva and Visnu, both Mahayana and Theravada Buddhism were significant actors at multiple levels of society giving witness to moments of religious florescence and dominance. The two most conspicuous examples of Buddhism’s impact are the vast architectural works associated with Jayavarman VII, the Angkorian king responsible for shifting state religion to a distinctly Mahayana form leading to the end of Brahmanic domination by the end of the 13th century, and the subsequent rise and permanent establishment of Theravada in Cambodia during the 14th century. While Buddhism has played a continuous role in Khmer culture since the 5th century evidence of its practice and impact through the pre-Angkorian to Angkorian periods remain substantially muted due in large part to the relative infrequency of specific temple dedications and discussion within the epigraphic sources. Recent research has taken important steps toward rectifying this gap in our understanding of Buddhist occupation and ritual functions around the lone Buddhist asrama of Yasovarman I in greater Angkor, the origins of the Theravada transition through sculptural and architectural decorative media, and more broadly as a secondary or primary religion within the corpus of Khmer inscriptions. These studies independently recognized important features of the practice, change, and function of Buddhism within the rise, expansion and ultimate decline of the Khmer Empire. However, what is lacking from these important benchmark studies is a holistic (social, political, economic, religious) and multi-scalar (object to landscape) assessment of Buddhist transition from a single Khmer location combining archaeological, epigraphic and material evidence. Innovative and comprehensive investigations in this model have been applied in India. No comprehensive study has yet been conducted within and around a comparable Buddhist center in Angkorian Cambodia. Identifying evidence of Buddhism, however, is complicated by the fact that the majority of preserved temples dedicated to the religion during the Angkorian period are restricted to the late 12th to 13th centuries and that the switch to Theravada did not produce such grandiose masonry architecture and state-level infrastructure. The lone site that may hold the key to elucidating the manifold aspects of Buddhism within Khmer history is Preah Khan of Kompong Svay.