1. The clinical records of 250 male nonpsychotic sex offenders, admitted consecutively to the psychiatric division of Bellevue Hospital over a period of thirteen months, were studied. Clinical data regarding type of offense, age, racial origin, nativity, education, religion, marital status, and previous offenses are presented.2. Pedophilia and exhibitionism were the most frequent types of offense, together comprising two-thirds of the cases. The remaining four types of offense—statutory rape, incest, sex relations associated with force, and homosexuality—together comprising one-third of the cases.3. The statutory rape group was, on the average, younger than the pedophilia and exhibitionism groups. There were 53 (22%) Negroes in the series. This represents a greater incidence of Negro offenders than would be expected from the population percentages in New York City.4. Fifty-six (23%) were of foreign birth. This represents a smaller incidence of sex offenders among the foreign born than would be expected from their ratio to the native-born population in New York City.5. Sixty-two (15.7%) had completed 8 grades of schooling. Of these 15 completed four years of high school and 9 had attended college. Of the remainder, 4 (1.7%) had attended ungraded school and 10 (4.1%) had no schooling whatsoever. The others had less than 8 grades of schooling.6. Only 64 (26.4%) were married and living with their wives at the time of the offense, as compared with 109(45%) who were single. The remainder were either divorced, separated or widowed.7. Seventy-seven (32%) had been previously charged with sex offenses, and 87 (38%) had been previously charged with non-sex offenses. The remainder had no past criminal record.8. The psychopathology of the sexual perversions in the main consists of faulty psychosexual development—"fixation" at an infantile or childhood level, or persistence of infantile attitudes toward infantile objects, resulting in an inability to attain sexually mature attitudes later in life.9. From a medico-legal and social standpoint, the pedophiliac sex offender is a problem of chief importance and when such an offender following completion of a sentence is still a potential menace, means should be adopted for further supervision. Psychiatric examination of all sex offenders should be made mandatory through legislative enactment. Through an educational program, the public and all who have the handling of sex offenders should be made acquainted with the potentialities for rehabilitation which can be offered in certain types of offenders through psychiatric methods, and should understand that purely penological measures are unsatisfactory.