In the mid-1940s at Columbia University School of Dental and Oral Surgery, Dr Irwin Mandel began a pioneering career in research on salivary chemistry in health and disease. It brought him an international reputation, an array of awards, and honorary degrees from prestigious universities. In the first half of his 50-year tenure at Columbia, he shared his commitment to research with the operation of a half-time private practice in Manhattan. Then, after giving up his practice, he became a full-time faculty member at Columbia as division head of preventive dentistry and community health, and concluded his service as associate dean for research. Dr Mandel has become recognized by his peers at Columbia and by the academic community across the United States as a symbol of integrity, both in his research and as a person. Shaped in childhood by a culture of caring in a community of Jewish immigrants to which his father was dedicated, he became well-known for his thoughtful mentoring of rising scientists. Additionally, for much of his life, he was a committed social activist.