His return to the American Academy in Rome from Syria in 1947 marked the beginning of the Academy's involvement in archaeological fieldwork in Italy with the excavations of the Latin colony of Cosa (Ansedonia) in southwestern Tuscany. Brown saw Cosa as a site that was useful a template for the archaeology of Latin colonies and mid-Republican Rome itself. Brown remained at the Academy as Professor-in-Charge of the Classical School and Director of Excavations from 1947–1952 and then returned to Yale as Professor of Classics where in addition to his teaching responsibilities he continued to be active in the publication of Dura-Europus and in the life of the American Schools of Oriental Research (ASOR), the offices of which were then in New Haven. He was Secretary of ASOR, 1955–1962; Master of Jonathan Edwards College, 1953–1956; and in collaboration with his Yale colleagues, Professors Lawrence Richardson, Jr. and Emeline Richardson, produced the second volume of the Cosa excavation reports, "The Temples of the Arx" ("MAAR" 1960). A generation of American Classical archaeologists and historians received their training under Brown at Cosa; notable among them are Lawrence Richardson, Jr., Emeline Hill Richardson, Russell T. Scott, and Stephen L. Dyson. The third volume on Cosa's forum and municipal buildings appeared after Brown's death.