The idea of stages provides a useful organizing framework around which to develop specific theories of initiation, progression, and regression in problem behaviors and specific intervention strategies to deal with the various phases of participation in these behaviors. By isolating populations at risk for progression from one behavioral stage to the next, it is possible to identify more accurately the factors affecting those transitions. The notion of stages is based on the premise that there is a regular ordering in participation in various behaviors. In contrast, the common syndrome perspective postulates that participation in any one behavior is an opportunistic response to environmental conditions on the part of individuals who share a certain proneness to deviance. Thus, the two notions confront a fundamental theoretical antithesis concerning the relative importance of common versus specific risk factors to explain the manifestations of different forms of deviance. Empirical studies suggest that both sets of factors may come into play in explaining adolescent drug use and other problem behaviors. Additional research, however, is needed to determine the existence of developmental patterns within and among different classes of problem behaviors in adolescence and preadolescence. 68 references, 3 figures.