The Institute for the Study of Antiquity and Christian Origins (ISAC) is an Organized Research Unit of the College of Liberal Arts, at The University of Texas at Austin. It was founded in 2002 and is currently under the direction of Dr. Geoffrey Smith, Associate Professor of Biblical Greek and Christian Origins and Fellow of the W. C. Nease Endowment.

As a graduate research center, ISAC is housed in the Department of Religious Studies, which boasts one of the top ranked graduate programs in Religion of the Ancient Mediterranean, where students and faculty study the Biblical world, Formative Judaism, and Early Christianity in their cultural contexts. ISAC fosters close connections with the study of the Greco-Roman world as well as the study of the ancient Middle East. The institute promotes the development of specialized, interdisciplinary graduate offerings and provides faculty and graduate students with research support in conjunction with the Department of Religious Studies.