This article estimates the prevalence and identifies risk factors of resident aggression and abuse in assisted living facilities. We conducted multivariate analyses of resident-level data from an analytic sample of 6,848 older Americans in the 2010 National Survey of Residential Care Facilities. Nationwide, 7.6% of assisted living residents engaged in physical aggression or abuse toward other residents or staff in the past month, 9.5% of residents had exhibited verbal aggression or abuse, and 2.0% of resident engaged in sexual aggression or abuse toward other residents or staff. Dementia and severe mental illness were significant risk factors for all three types of resident aggression and abuse. Resident aggression and abuse in assisted living facilities is prevalent and warrants greater attention from policy makers, researchers, and long-term care providers. Future research is needed to support training and prevention efforts to mitigate this risk.