This study examined associations between the development of adolescent alcohol, cigarette, and marijuana use and risky sexual behavior, over time, using latent growth modeling methodology. Gender differences in the development and relationships between use of substances and risky sexual behavior were also examined. Participants were 257 adolescents (mean age = 15.96 years) assessed at three time points over an 18-month period. The intercepts of marijuana with cigarettes and alcohol, and all three substances with risky sexual behavior were significantly related. Development of the three substances showed similar patterns and development of cigarette use covaried with development of risky sexual behavior. There were no significant differences for boys and girls in these relationships. Results are discussed in relation to the need for greater understanding of nonsexual and sex-related problem behaviors and for analyses examining development and change in these behaviors during adolescence.