Although designed to assess attitude change during treatment of youthful offenders, the JI has evolved into an objective instrument for identifying levels of delinquency and for defining personality typologies of both delinquents and nondelinquents. The present study's sample included 80 nondelinquent controls, 77 youths with acting out or minor behavior problems, 70 youths placed in an institutional setting but not yet adjudged delinquent through formal court proceedings, and 70 formally charged and adjudged delinquents. Subjects were white and American Indian and had a mean age of 13.6 years. The JI items were read aloud to the subjects either individually or in small groups. Mean scores were calculated for each of the four groups and analyses of variance were done for overall group divergences, with specific paired comparisons between groups using the Newman-Keuls tests. Results showed significant differences among groups on social maladjustment, value orientation, autism, manifest aggression, and the asocial index. Control subjects consistently had the lowest scores. Paired comparisons showed no significant differences between noncharged delinquents and charged delinquents on 10 of the 11 subscales, but a clear stepwise difference was found between each of the four groups on the asocial index. A progressive increase, directly related to delinquent involvement, was found in T scores on the asocial index. Findings demonstrate the validity of the JI and the particular usefulness of the asocial index. Further research should focus on the predictive validity of the JI since its present usefulness as only a descriptive instrument gives it limited application. One table, a reference note, and 25 references are provided.