Objective: Childhood sexual abuse (CSA) is associated with elevated risk of early marijuana use and cannabis use disorder (CUD). Both the prevalence of CSA and the course of marijuana use differ between African Americans and European Americans. The current study aimed to determine whether these differences manifest in racial/ ethnic distinctions in the association of CSA with early and problem use of marijuana. Method: Data were derived from female participants in a female twin study and a high-risk family study of substance use (n = 4,193, 21% African-American). Cox proportional hazard regression analyses using CSA to predict initiation of marijuana use and progression to CUD symptom(s) were conducted separately by race/ethnicity. Sibling status on the marijuana outcome was used to adjust for familial influences. Results: CSA was associated with both stages of marijuana use in African-American and European-American women. The association was consistent over the risk period (hazard ratio [HR] = 1.57, 95% confidence interval [CI] [1.37, 1.79] for initiation; HR = 1.51, 95% CI [1.21, 1.88] for CUD symptom onset) in European-American women. In African-American women, the HRs for initiation were 2.52 (95% CI [1.52, 4.18]) before age 15, 1.82 (95% CI [1.36, 2.44]) at ages 15–17, and nonsignificant after age 17. In the CUD symptom model, CSA predicted onset only at age 21 and older (HR = 2.17, 95% CI [1.31, 3.59]). Conclusions: The association of CSA with initiation of marijuana use and progression to problem use is stable over time in European-American women, but in African-American women, it varies by developmental period. Findings suggest the importance of considering race/ethnicity in prevention efforts with this high-risk population.