A native of Bristol, Tennessee, Caldwell is a graduate of Furman University, where he majored in history with a concentration in classical studies, and he received his Ph.D. in history from Princeton University. His graduate training included specializations in late antiquity and Roman law. Before coming to ASU, he taught at Samford University, the University of Georgia, and Furman University. His professional interests include ancient and medieval coinage, military history, and European law and legal history. His current book manuscript uses civil wars to explore the decline of the later Roman Empire in the Balkan region.