This dissertation used an evolutionary approach to examine the antecedents and outcomes to early pubertal development in girls in four major ethnic groups (i.e., European American, African American, Hispanic American, and Asian American). In the first study, logistic regressions were conducted to investigate the links between socioeconomic status (SES), parenting behaviors, and father absence to pubertal development across and within ethnic groups. SES and father absence predicted earlier pubertal development among European, African, and Hispanic Americans but not for Asian Americans. In the second study, growth curves were estimated for sexual outcomes across ethnic groups. Early developing European and African American girls had higher levels of sexual risk and pregnancy into adulthood. Puberty did not predict outcomes for Hispanic and Asian American girls. Overall, the findings from both studies revealed the importance of investigating childhood environmental contexts, puberty, and sexual health outcomes using an evolutionary perspective.