Theodore Lidz (1 April 1910 – 16 February 2001) was an American psychiatrist best known for his articles and books on the causes of schizophrenia and on psychotherapy with patients with schizophrenia. An advocate of research into environmental causes of mental illness, Lidz was a notable critic of what he saw as a disproportionate focus on biological psychiatry. Lidz was a Sterling Professor of Psychiatry at Yale University. In his lifetime, he did a great amount of research on interpersonal causes of schizophrenia.
Born in New York City and raised on Long Island, the son of Israel Isador Lidz, president of a button and novelties firm in Manhattan, and Esther Shedlinsky. Lidz attended Columbia College and the Columbia University College of Physicians and Surgeons. After two years of medical internship at Yale-New Haven Hospital, he became an assistant in neurology at National Hospital, Queen's Square in London. He took his residency in psychiatry at Johns Hopkins University. It was while studying there with Adolf Meyer that Lidz learned to examine personal history and experience as sources of psychotic as well as neurotic disorders.
During his residency, Lidz met Ruth Maria Wilmanns, a German-born psychiatrist who had fled the Nazi regime in 1934 and arrived at Johns Hopkins in 1937. They were married in 1939, and they shared their professional interests in psychiatry as well as a love of art until her death in 1995.
In January 1942, Lidz enlisted in the Army and served in New Zealand, Fiji and Burma. In Fiji, as the hospital's only psychiatrist, he had several hundred psychiatric casualties from Guadalcanal in his personal care.