The purpose of this study was to examine domains of personality, family, and peer variables and their relationship to the qualitative (stage) and quantitative (frequency) aspects of adolescents' drug use. Black (245) and white (418) high school freshmen and sophomores served as subjects. Analysis indicated that the same personality and peer factors differentiated between the quantitative as well as the qualitative drug groups. However, more family variables were related to stage than to frequency of use. Several models were proposed for examining the interrelationships of the three domains and associations with stage and frequency of drug use. The data supported an independent model for the stage groups; that is, each of the three domains (personality, family, and peer) was associated with the adolescents' stage of drug use independent of the latter's relationship with the remaining domains. For the frequency groups, the data supported a mediational model; that is, the family and personality domains were associated with the peer domain which in turn was associated with frequency of drug use. One interpretation advanced is that stage of drug use is sensitive to an array of factors from all three domains whereas the frequency with which adolescents use the drug depends on the current influence of the peer group.