The National Household Survey on Drug Abuse (NHSDA) has shown that the rate of marijuana use among youth has more than doubled since 1992. Similar trends are noted across all subgroups studied. At the same time, the percentage of teens perceiving a "great risk" from smoking marijuana has declined. Negative effects of marijuana use are listed. NHSDA methodology is presented and the possibility of underreporting of drug use by youths in their homes is noted. This study, a further analysis of the youth mental health self-report data, examines the characteristics of past year marijuana users age 12 to 17 in data from the 1994, 1995, and 1996 samples. Self-reported problem behaviors associated with marijuana use were withdrawal, somatic complaints, anxiety and depression, social problems, thought problems, attention problems, delinquent behavior, aggressive behavior, and criminal behavior. A user profile is presented. Generally, the more frequent the marijuana use behavior reported, the more likely the youths were to report problem behaviors. Eleven tables present frequency of use by age and selected demographic characteristics, and percentage and confidence intervals for each of the problem behaviors is reported. (EMK)