Purpose: This study investigates associations of childhood adversities (CAs) with lifetime prevalence, 12-month prevalence, and 12-month persistence of mental disorders in a large cross-national sample of university students. Methods: Data came from epidemiologic surveys carried out by the World Mental Health International College Student (WMH-ICS)Initiative across 18 countries (n=60,719). The web-based surveys screened for lifetime and 12-month prevalence and age-of-onset of common DSM-5 disorders (Major Depressive Disorder, Bipolar I/II Disorder, Generalized Anxiety Disorder, Panic Disorder, Posttraumatic Stress Disorder, Alcohol and Drug Use disorders, Attention-Deficit/Hyperactivity Disorder) and five types of CAs (family dysfunction, emotional abuse, physical abuse, sexual abuse, neglect). Multivariable Poisson regression models estimated associations of CA type, number, and frequency with disorders. Results: The majority of incoming students reported exposure to at least one CA (64.9%), including 50.0 % family dysfunction, 42.2 % emotional abuse, 21.2 % physical abuse, 18.8 % neglect, and 5.0 % sexual abuse. Lifetime and 12-month disorders were significantly associated with CAs in multivariable models, although associations with disorder persistence were weaker. Population attributable risk proportions of 12-month disorders associated with CAs were in the range of 40.7–61.0 % for anxiety and mood disorders and 13.5–55.2 % for substance use disorders. Conclusion: Six out of ten university students arrive at university having been exposed to CAs. These students have substantially higher risk of mental disorders than other students, primarily due to associations with lifetime risk rather than persistence. Given the considerable distress and impairment caused by mental disorders, these results underscore the need for primary and secondary prevention efforts.