Among over 5 million people in the USA with dementia, neuropsychiatric symptoms (NPS) are almost universal, occurring across disease etiology and stage. If untreated, NPS can lead to significant morbidity and mortality including increased cost, distress, depression, and faster disease progression, as well as heightened burden on families. With few pharmacological solutions, , identifying nonpharmacologic strategies is critical. We describe a randomized clinical trial, the Dementia Behavior Study, to test the efficacy of an activity program to reduce significant existing NPS and associated caregiver burden at 3 and 6 months compared to a control group intervention. Occupational therapists deliver 8 in-home sessions over 3 months to assess capabilities and interests of persons with dementia, home environments, and caregiver knowledge, and readiness from which activities are developed and families trained in their use. Families learn to modify activities for future declines and use strategies to address care challenges. The comparison group controls for time and attention and involves 8 in-home sessions delivered by health educators who provide dementia education, home safety recommendations, and advanced care planning. We are randomizing 250 racially diverse families (person with dementia and primary caregiver dyads) recruited from community-based social services, conferences and media announcements. The primary outcome is change in agitation/aggression at 3 and 6 months. Secondary outcomes assess quality of life of persons with dementia, other behaviors, burden and confidence of caregivers, and cost effectiveness. If benefits are supported, this activity intervention will provide a clinically meaningful approach to prevent, reduce, and manage NPS.