The authors examined co-occurrence among a wide range of adolescent problem behaviors: alcohol, smoking, marijuana, hard drugs, sexual activity, major and minor delinquency, direct and indirect aggression, and gambling. Using a large self-report survey of high school students, confirmatory factor analysis was used to test the problem syndrome model proposed by problem behavior theory. A 3-factor model provided better overall fit than did a single problem syndrome factor model. Contingency table analyses were used to examine the co-occurrence of problem behaviors at different levels of involvement within individuals, as well as relative risk ratios. Analyses offered modest support for a limited problem syndrome encompassing the report of high-risk involvement with alcohol, minor delinquency, direct aggression, and, to a lesser extent, marijuana. For each problem behavior, the majority of adolescents did not report high-risk involvement, and only a minority reported any involvement with multiple behaviors.