In recognition of the two hundredth anniversary of the birth of Isaac Ray (1807–1881), the father of American forensic psychiatry, the author explores the influence of phrenology on Ray's early thought. Phrenology, popular at the time of the founding of the American Psychiatric Association in 1844, was a transitional discipline between spiritually based theories of mind and the materialistic concepts that continue to dominate psychiatric thought. Ray, a vocal advocate of phrenology during his days as a general practitioner in Maine, said little about the science in his Treatise on the Medical Jurisprudence of Insanity in 1838. Yet, remnants of phrenology can be found in his formulations of the biological bases of behavior well into his career. The author highlights the parallels between phrenological thought and modern biological psychiatry in their potential to inform legal matters.