American psychologist and physician who advocated the study of abnormal psychology (psychopathology) and formulated concepts such as the neurogram, or neurological record of psychological behaviour, and the coconscious, a parallel, possibly rival, well-organized system of awareness comparable to the ordinary, familiar consciousness.

A practicing physician, Prince taught neurology at the Harvard Medical School (1895–98) and at Tufts College Medical School, Medford, Massachusetts (1902–12). Among the first to use hypnosis for exploring psychopathology and for psychotherapy, he recognized motivational forces of emotional conflict.

In 1906 Prince founded the Journal of Abnormal Psychology, which he edited until 1929, and wrote The Dissociation of a Personality (1906), the study of a multiple personality (dissociative identity disorder). Another work was The Unconscious (1914). Prince was long interested in bringing academic psychology and clinical psychology together with a uniform set of concepts. He founded the Harvard Psychological Clinic (1927). His last work was Clinical and Experimental Studies in Personality (1929).