Objective: International appeals call for interventions to prevent aggression and other behavioral problems in individuals with dementia (IWD). Aggression Prevention Training (APT), based on intervening in three contributors to development of aggression (IWD pain, IWD depression, and caregiver–IWD relationship problems) aims to reduce incidence of aggression in IWD over 1 year. Design: Randomized, controlled trial. Setting: Three clinics that assess, diagnose, and treat dementia.