Some extant theory and empirical research suggests that youth problem behaviors, such as substance abuse and delinquency, reflect a single underlying dimension of behavior, whereas others suggest there are several different dimensions. Few studies have examined potential international differences in the structure of problem behavior, where cultural and policy differences may create more variation in behavior and different structures. This study explored the structure of problem behavior in two representative samples of youth (ages 12-17) from Maine and Oregon in the United States (N = 33,066) and Victoria, Australia (N = 8,500). The authors examined the degree to which data from the two countries produce similar model structures using indicators of problem behavior. Results show that the data are best represented by two factors, substance use and delinquency, and there appear to be more similarities than differences in the models across countries. Implications for understanding problem behavior across cultural and developmental groups and practical and policy implications are discussed. (Contains 1 note, 4 tables and 2 figures.)