The study found that the factors that influenced decisionmaking about sexual behavior among Latina youth were related to individual personality characteristics, family values, and peer/partner characteristics. The strongest of these factors in preventing early initiation into sexual intercourse was a sense of personal control over behaviors in accordance with personal values and life goals. Factors related to personal values and life goals were strong family expectations about educational achievement, negative parental messages about premarital sex and pregnancy, resistance to the influence of peers and partners, a preference for speaking Spanish, and a small age difference between the young girls and their first sexual partners. These findings should inform future programs for Latinas designed to prevent risky sexual behaviors. The focus should be on increasing feelings of personal control over decisions about sexual behavior and helping Latino parents to communicate strong messages about educational achievement, pregnancy, and sexual behavior. The study enrolled a convenience sample of predominantly Mexican-American adolescents and young adult women from the west side of Chicago. A total of 271 Latinas were included in the analysis. Prior qualitative research with young women from the target population and findings from the existing literature were used to develop the theoretical framework for the development of a quantitative instrument, which was pretested. Bivariate and multivariable analyses were performed in order to identify factors linked with age at first sexual intercourse. 2 tables, 61 references, and appended Language-based Acculturation Scale