A study comparing four models of substance misuse were performed. Alcohol drinking, tobacco use, sniffing of a dissolvent and cannabis use were proposed to depend on one, two, three, or four latent factors. In confirmatory factor analyses the fit of the models were tested against empirical data from a group of adolescent school pupils. The result suggested that a two-factor model, legal and illicit use, was valid. Another conclusion is that alcohol consumption precede both legal and illicit drug use and that it probably is several stepwise pathways in the development of a misuse. Since earlier studies show that use of cannabis is strongly associated with behavioral problems parents should be careful to watch their adolescents' behavior and block the pathway to illicit drugs.