Rates of unintended pregnancy and STI acquisition are most prevalent during the transition from adolescence to adulthood, as young women become sexually active, and tend to experience major shifts in living arrangements, occupation, and relationships. In the United States, these changes may disrupt already tenuous health care contacts or the necessity of reproductive health care may become more acute without a corresponding level of knowledge about how to navigate the health care system. The proposed study will investigate how young women use health care, differences in access among women with different resources and life circumstances, and the contributions of health care use to contraceptive use and other reproductive health outcomes. Specifically, the study will: 1) examine young women's health care access across the transition from adolescence to early adulthood; 2) investigate the relationship of health care to reproductive health outcomes; 3) examine the contribution of health care to sociodemographic and racial/ethnic disparities in reproductive health outcomes; and, 4) develop measures related to health care use during the transition from adolescence to early adulthood. Secondary analysis of data from the National Survey of Family growth and the National Longitudinal Survey of Adolescent Health will be conducted, and a qualitative study of young adult women will be undertaken.