Background: People living with dementia (PLWD) and caregivers are adversely impacted by lack of meaningful activity leading to worse symptoms and impaired quality-of-life. There is a critical need to develop effective and well-tolerated treatments that mitigate clinical symptoms, engage PLWD and support caregiver wellbeing. We tested whether, compared to attention control, the Tailored Activity Program (TAP) reduced clinical symptoms and health-related events, and improved caregiver wellbeing, and if TAP activities were well-tolerated. Methods: We conducted a single-blind randomized controlled trial among 250 dyads recruited from Baltimore-Washington DC (2012–2016) with a dementia diagnosis and clinically significant agitation/aggression. Dyads were randomized to TAP (n = 124) or attention control (n = 126), and interviewed at baseline, 3 (endpoint) and 6-months (follow-up) by interviewers masked to group allocation. TAP assessed PLWD abilities/interests, instructed caregivers in using prescribed activities, and provided dementia education and stress reduction techniques. Attention controls received disease education and home safety tips. Both groups had up to 8 home visits over 3-months. The primary outcome was frequency by severity scores for agitation/aggression subscales of Neuropsychiatric Inventory-Clinician using caregiver ratings. Secondary outcomes included number of instrumental (IADL) and activities of daily living (ADL) needing assistance, caregiver wellbeing, and confidence using activities. Health-related events (PLWD death, hospitalizations, caregiver hospitalization, depression) and perceived study benefits were captured over 6 months. PLWD tolerability of prescribed activities was examined. Results: Of 250 dyads, most caregivers were female (81.2 %, n = 203), non-spouses (54.4 %, n = 136), white (59.2 %, n = 145) or African American (36.7 %, n = 90) with mean age = 65.4 (SD = 12.6). PLWD were mostly female (63.2 %, n = 158) with mean age = 81.4 (SD = 7.9), and mean MMSE = 14.3 (SD = 7.8). At 3-months, compared to controls, TAP conferred no benefit to agitation/aggression (p = 0.43, d = 0.11), but resulted in less IADL (p = 0.02, d=-0.33), and ADL (p = 0.04, d=-0.30) assistance, improved caregiver wellbeing (p = 0.01, d = 0.39), and confidence using activities (p = 0.02, d = 0.32). By 6-months, 15 PLWD in TAP had ≥ 1 health-related event versus 28 PLWD in control, demonstrating 48.8 % improvement in TAP (p = 0.03). TAP caregivers were more likely to perceive study benefits. Prescribed activities were well-tolerated. Conclusions: Although TAP did not benefit agitation/aggression, it impacted important outcomes that matter to families warranting its use in dementia care. Clinical trial registration: Clinicaltrials.gov # NCT01892579 at https://clinicaltrials.gov/; Date of clinical trial registration: 04/07/2013; Date first dyad enrolled: 15/11/2013.