In many sub-Saharan African countries, young women face decreasing educational opportunities, age asymmetries between sexual partners, and high prevalence of HIV infection. This study draws upon data from the 2002 Cameroon Adolescent Reproductive Health Survey to analyze the determinants of young women's perceived ability to refuse sex in urban Cameroon. Our findings are consistent with predictions of social exchange theory: young women's status characteristics predict their vulnerability differently under different circumstances, and, overall, young women report having a lower ability to refuse sex in their relationships with men who offer to pay their school fees than in their relationships with men in positions of power over them. The costs and benefits of sexual exchanges made in order to continue one's education increase simultaneously in a context of declining enrollments and spreading HIV infection. When educational aspirations exceed opportunities, policy supporting access to education could reduce young women's need to employ their sexual resources in order to invest in their future.