This study assessed the relation of socioeconomic status (SES), family structure, and race/ethnicity to adolescent sexual behaviors that are key determinants of pregnancy and sexually transmitted diseases (STDs). The 1992 Youth Risk Behavior Survey/Supplement to the National Health Interview Survey provided family data from household adults and behavioral data from adolescents. Among male and female adolescents, greater parental education, living in a 2-parent family, and White race were independently associated with never having had sexual intercourse. Parental education did not show a linear association with other behaviors. Household income was not linearly related to any sexual behavior. Adjustment for SES and family structure had a limited effect on the association between race/ethnicity and sexual behaviors. Differences in adolescent sexual behavior by race and SES were not large enough to fully explain differences in rates of pregnancy and STD infection. This suggests that other factors, including access to health services and community prevalence of STDs, may be important mediating variables between SES and STD transmission and pregnancy among adolescents.