The study investigated whether personality tests differentiated between drug and alcohol users among juvenile offenders. Subjects included 108 juvenile offenders who ranged in age from 15 to 21 years, 94 male and 14 female. All had pleaded guilty to a criminal offense and had recently been given a conditional discharge for a period of at least 1 year. The EPQ measured psychoticism, extraversion, neuroticism, and social desirability, while the GSS assessed the extent to which subjects internalized values of society and became socialized. A specifically designed questionnaire measured drug and alcohol use. Of the 108 study participants, 105 (97 percent) reported having consumed alcohol and 32 (30 percent) reported weekly or more frequent alcohol use. Significant differences were found between drug users and those not using drugs on the GSS and on EPQ lie and addiction scales. No major differences, however, were observed between the two groups in the EPQ addiction scale when the lie scale was used as a covariate. There was a clear overlap between illicit drug use and alcohol use in that the two groups were represented by many of the same people. For example, of the 32 frequent alcohol users, 27 (84 percent) also reported having used illicit drugs. 17 references and 2 tables