John G. Gunderson, MD, is professor of psychiatry at Harvard Medical School. At McLean Hospital, he is director of the Borderline Center’s clinical, training, and research programs. Gunderson is widely recognized as the father of the borderline diagnosis. He is responsible for seminal research on the diagnosis, its course, its origins, and its treatment. These contributions have always been anchored within his role as a clinician whose practices are practical and compassionate.