Background: Given growing numbers of older adults with mental and substance use disorders (MSUDs), this study examined the association between ten types of adverse childhood experiences (ACEs) and lifetime MSUDs among those aged 50+. Methods: Data (N=14,738 for the 50+ age group) came from the 2012 to 2013 National Epidemiologic Survey on Alcohol and Related Conditions. Using multivariable binary logistic regression analyses, we examined relationships between ten ACEs and six lifetime MSUDs (major depressive disorder (MDD) and anxiety, post-traumatic stress, alcohol use, drug use, and nicotine use disorders). Gender differences were examined using tests of interaction effects and gender-separate logistic regression models. Results: Of the sample, 53.2% of women and 50.0% of men reported at least one ACE. For both genders, parental/other adult's substance abuse was the most prevalent (22.6%), followed by physical abuse, and emotional neglect. Child abuse and neglect and parental/other adult's mental illness and substance abuse had small but consistently significant associations with MSUDs (e.g., odds ratio = 1.28, 95% CI= 1.12-1.46 for parental/other adult's substance misuse and MDD). Although the relationship between total number of ACEs andMSUDs was cumulative for both men and women, the associations of physical abuse, sexual abuse, emotional neglect, and parental separation/divorce with MSUDs were stronger among men. Conclusions: This study underscores the significant yet modest association between ACEs and lifetime MSUDs in late life. More research is needed to investigate why ACEs seem to have greater effects on older men and to discern the sources of gender differences in ACEs' effects.