Substance abuse experimentation may be one of several types of problem behaviors. Data from 99 Caucasian women interviewed in alcoholism treatment (19-29 years old) were used to test a developmental model of substance experimentation. Respondents were classified into three groups based on their use prior to age 15: nonusers, users of alcohol only, and users of alcohol and other drugs. Family history of alcoholism was not related to childhood anxiety and impulse control problems. Childhood anxiety and impulse control problems predicted adolescent emotional and impulse control problems but did not differentiate early experimenters. Whereas adolescent emotional problems were not related to early experimentation, early drug and alcohol users were significantly more likely to have engaged in other impulsive behaviors (e.g., running away from home, trouble with school authorities) than were nonusers or users of alcohol only. Alcoholism prevention programs, therefore, would do well to target youth who exhibit acting-out behaviors as a high-risk group for early alcohol and drug use.