Dr. Marmor was born in London, England, and received his A.B. (1930) and M.D. (1933) from Columbia University. He interned and started psychiatric residency at St. Elizabeths Hospital in Washington, D.C. (1933–35), which he later completed at the Brooklyn State Hospital. From 1935–37, he trained in neurology in New York. He received psychoanalytic training at the New York Psychoanalytic Institute (1948). He became a training analyst for the Southern California Psychoanalytic Institute. During World War II, he was in the U.S. Public Health Service, stationed in Florida.
Dr. Marmor moved to Los Angeles in 1947 and entered full time private practice, providing consulting and advisory services to public and private agencies and facilities. He was a consultant to Veteran Affairs (1942–50); Los Angeles County Bureau of Adoptions (1954–60); Director of the Division of Psychiatry, Cedar Sinai Hospital (1965–72); Franz Alexander Professor of Psychiatry, University of Southern California (1922) and later Emeritus Professor of Psychiatry, University of California, Los Angeles; consultant to the Institute of Crime and Delinquency; visiting professor, School of Social Welfare, University of California, Los Angeles (1952–64); and Chairman of the Research and Review Committee on Social Problems for the National Institute of Mental Health (1972–73).
Dr. Marmor was an active member of professional organizations, including the Group for the Advancement of Psychiatry, President (1973–75); the AMA; the Academy of Psychoanalysis, President (1965–66); the Advancement of Science; and the American College of Psychiatrists, from which he received the Bowis Award. He also received a Silver Medal from Columbia University College of Physicians and Surgeons (1967) and an honorary Doctor of Humane Letters from Hebrew Union College in Los Angeles.
Dr. Marmor was elected Vice President (1972–73) and served as President of the American Psychiatric Association (1975–76).