Study participants were adolescents and their parents referred by the juvenile justice (80 percent), education (10 percent), or social welfare (10 percent) systems for drug abuse treatment. This study focused on the intake evaluation. Seventy-four percent of the youths were African-American, 18 percent non-Hispanic white, and 8 percent Hispanic. The median yearly family income from all sources was between $11,000 and $13,000. Forty-three percent of the families were on public assistance. Consumption of drugs was measured by an adaptation of the timeline follow-back method (TLFB; Sobell and Sobell, 1992). The extent of externalizing and internalizing symptomatology was measured by the Child Behavior Checklist and the Youth Self-Report. The externalizing dimension included the delinquent behavior and aggressive behavior syndromes; and the internalizing grouping included the withdrawn, somatic-complaints, and anxious/depressed syndromes. Family functioning was measured by the conflict and cohesion scales of the Family Environment Scale. Findings show that male and female adolescent substance users differed in several clinically meaningful ways. The results from a discriminant function analysis indicate that substance-using adolescents referred to treatment were distinguished especially by the greater degree to which girls had internalizing symptoms and family dysfunction. The clinical implications of these gender differences are discussed. 2 tables and 80 references