Several studies have shown an association between early sexual initiation and involvement in antisocial/delinquent behavior and substance use (Kinsman, Romer, Furstenberg, & Schwarz, 1998; Mott et al., 1996; National Center on Addiction and Substance Abuse, 1999; Smith, 1997; Weinbender & Rossignol, 1996). A longitudinal study of at-risk male adolescents in Oregon shows that teens who initiate sexual intercourse in grades 7-8 display greater antisocial/delinquent behavior, exhibit higher levels of substance use in adolescence, and have arrest rates almost double those of their peers who initiate sexual intercourse in grades 9-11 (Capaldi et al., 1996). Among white adolescents, greater participation in and tolerance of deviance, and having relatively more friends who engage in problem behaviors are associated with an earlier age of sexual initiation (Costa, et al., 1995).

Multiple studies also illustrate an association between substance use and risky sexual behaviors. Alcohol and drug use among adolescents and their friends is related to nonuse of condoms and birth control (Kowaleski-Jones & Mott, 1998; Middleman et al., 1995; Shrier et al., 1996), putting teens at risk of pregnancy and STIs (Boyer et al., 1999; Middleman et al., 1995). Use of alcohol and illicit drugs also is associated with a higher probability of adolescents having had multiple sexual partners (Middleman et al., 1995; Millstein & Moscicki, 1995; National Center on Addiction and Substance Abuse, 1999; Santelli et al., 1998; Shrier et al., 1996; Valois, Oeltmann, Waller, & Hussey, 1999). For male teens, daily cigarette use and frequency of cocaine and alcohol use are linked to a greater likelihood of involvement in a pregnancy (Guagliardo, Huang & D'Angelo, 1999; Pierre et al., 1998; Spingarn & DuRant, 1996).