Although students are encouraged to disclose peer sexual harassment, no studies have investigated disclosure among adolescents. This study investigated the extent of peer sexual harassment disclosure, to whom students make disclosures, and different characteristics associated with disclosure. Three-wave annual data from middle-school students (T1: age 10, N = 448) were analyzed. The findings showed that half of sexually harassed students made disclosures, most often to friends. Disclosure to adults declined across time. Slight gender differences were found, with girls being more likely to make a disclosure. Logistic regressions showed that individual (e.g., self-assertive efficacy) and social characteristics (e.g., social support) increased disclosure, but the results were inconsistent. This study provides a unique contribution by showing that much of the sexual harassment occurring within school remains undisclosed. This points toward the importance of early intervention, since sexual harassment becomes increasingly hidden from adults as students progress through middle school.