Janet Thornton (1881–1963) was the director of social services at Columbia-Presbyterian Medical Center in New York City from 1924 to 1947. Drawing on previously unexamined archival letters and documents, this article presents a professional and personal perspective on Thornton’s life. Restoring her to the historical record on hospital social work brings into focus the foundations of present-day social work practice in health care settings and adds new insights into the role of women in the burgeoning profession.