This study examines receipt of formal sex education as a potential mechanism that may explain the observed associations between disability status and contraceptive use among young women with disabilities. Using the 2011-2017 National Survey of Family Growth, we analyzed data from 2861 women aged 18 to 24 years, who experienced voluntary first sexual intercourse with a male partner. Women whose first intercourse was involuntary (7% of all women reporting sexual intercourse) were excluded from the analytic sample. Mediation analysis was used to estimate the indirect effect of receipt of formal sex education before first sexual intercourse on the association between disability status and contraceptive use at first intercourse. Compared to nondisabled women, women with cognitive disabilities were less likely to report receipt of instruction in each of 6 discrete formal sex education topics and received instruction on a fewer number of topics overall (B = -0.286, 95% CI = -0.426 to -0.147), prior to first voluntary intercourse. In turn, the greater number of topics received predicted an increased likelihood of contraceptive use at first voluntary intercourse among these women (B = 0.188, 95% CI = 0.055-0.321). No significant association between noncognitive disabilities and receipt of formal sex education or contraceptive use at first intercourse was observed. Given the positive association between formal sex education and contraceptive use among young adult women with and without disabilities, ongoing efforts to increase access to formal sex education are needed. Special attention is needed for those women with cognitive disabilities.