This longitudinal population-based study examined pathways to nonsuicidal self-harm (NSSH) in relation to childhood sexual abuse (CSA), assault victimization in early adulthood, posttraumatic stress disorder symptomatology (PTSD), and other mental disorders. At age 21,476 men and 455 women completed interviews on assaultvictimization, PTSD, andother mental disorders. At age 26, they completed independent interviews on self-harm and childhood sexual abuse (CSA). Multivariate logistic regression analyses were conducted to determine predictors for NSSH at age 26. For men, anxiety and depressive disorders at age 21 were the only significant predictors of NSSH at age 26. For women, victimization, PTSD, and other anxiety disorders at age 21 all significantly predicted NSSH. CSA predicted later NSSH only indirectly, by increasing the risk of anxiety disorders among men and of assault victimization among women. In conclusion, pathways to nonsuicidal self-harm differed by sex. For women there were direct links with assault victimization and PTSD in early adulthood, whereas for men only internalizing disorders predicted future NSSH.