Using 3 years of data from the National Household Survey on Drug Abuse, we examine the distribution of drug use among adolescents aged 12-17 years by family structure. In addition, we investigate the plausibility of two hypotheses that purport to explain the association between family structure and adolescent behavior, namely economic resources and residential mobility. The results of cross-tabulations and multivariate logistic regression models indicate that the risk of drug use, including problem use, is highest among adolescents in father-custody families (father-only and father-stepmother families), even after controlling for the effects of sex, age, race-ethnicity, family income, and residential mobility. The risk of drug use is lowest in mother-father families. Economic resources and residential mobility fail to explain these relationships, thus casting doubt on their ability to explain the association between family structure and an important adolescent behavior. Key Words: adolescent, alcohol, drug use, family structure marijuana. The development and consequences of adolescent drug use are important social issues. Adolescents who use drugs are at heightened risk of low academic achievement, high school dropout, early sexual initiation, teenage nonmarital pregnancy, troubled interpersonal relationships, and marital disruption in adulthood (Johnson & Kaplan, 1990; Newcomb & Bentler, 1988). A parallel line of research demonstrates that each of these outcomes is also associated with residence in singleparent or stepparent families (Astone & McLanahan, 1991, 1994; Downey, 1994, 1995; Downey & Powell, 1993; McLanahan & Sandefur, 1994; Wu, 1996). Although the link between family structure and adolescent drug use has been explored in a number of previous studies (Flewelling & Bauman, 1990; Hoffmann, 1994, 1995; Needle, Su, & Doherty, 1990; Thomas, Farrell, & Barnes, 1996), there are several lessons from the more general research on family structure that should be applied to research on adolescent drug use. The first lesson is that research on the relationship between family structure and adolescent drug use requires large samples to distinguish precise effects. Most studies have been forced to rely on categorization schemes that do not recognize potential differences between father-custody and mother-custody families. For example, much of the research in this area has assessed differences between single-mother families and mother-father families (Hoffmann, 1993; Thomas et al., 1996) or among single-parent, stepparent, and mother-father families (Flewelling & Bauman, 1990; Hoffmann, 1995; Needle et al., 1990). Yet a key result that has emerged from the general literature about family structure is that there are important differences between adolescents in mother-stepfather and father-stepmother families and between those in single-mother and single-father families (Ambert, 1986; Downey, 1995; Downey & Powell, 1993; Lee, Burkham, Zimiles, & Ladewski, 1994). In general, adolescents who reside with their mothers fare better than those who reside with their fathers in both single-parent and stepparent families. Given the small proportion of adolescents who reside with fathers but not with mothers (Bianchi, 1995; U.S. Bureau of the Census, 1993), it is not surprising that many studies of family structure and adolescent drug use, which often rely on small samples, have not heretofore distinguished the effects of father versus mother absence from the family. A second lesson concerns the theoretical models used to explain the effects of family structure on adolescent outcomes. Much of the research on family structure and adolescent drug use has been descriptive. A typical approach is to examine the distribution of drug use by family structure and then control for various demographic characteristics to determine if the relationships persist. Although this provides important information about the association between family structure and drug use, it fails to explain theoretically why this association exists. …