This application proposes a cluster randomized trial to evaluate an innovative staff intervention targeting resident-to-resident elder mistreatment (R-REM) in 6 intervention and 6 control assisted living residences (ALRs). Data will be collected at baseline, 6- and 12-months. We define R-REM as negative and aggressive physical, sexual, or verbal interactions between residents, that in a community setting would likely be construed as unwelcome and have high potential to cause physical and/or psychological distress. R-REM is a serious behavioral problem that has a negative impact on the quality-of-life and physical well-being of residents with and without Alzheimer’s disease and related dementias living in congregate settings. The applicant team is uniquely positioned to conduct this project because of its expertise, multidisciplinary composition, and its previous successful collaborative efforts. Aim 1 (A1). Enhance staff knowledge of R-REM Aim 2 (A2). Enhance staff recognition, reporting and care planning related to R-REM Aim 3 (A3). Evaluate the impact of the staff intervention on resident falls, accidents and injuries and on quality of life using a prospective experimental design that derives information from five sources: (1) Resident interviews (2) Staff informants (3) Observational data (4) Chart and (5) Incident/accident report data. Primary Hypothesis: The frequency of falls, accidents and injuries will decrease in the intervention group, relative to the comparison group after implementation of the training intervention. Secondary Hypotheses: 1. Resident quality-of-life as measured by affective state will improve in the intervention group, relative to the comparison group after implementation of the training intervention. 2. Resident behavior problems will decline in the intervention group, relative to the comparison group after implementation of the training intervention. Resident behaviors will mediate the relationship between the intervention and the falls/accidents/injuries outcome. R-REM has been identified as an important problem in long-term care settings, and our earlier studies identified significant behavioral problems in these settings. However, to our knowledge no interventions targeted at staff have been proposed or tested. The proposed trial is thus timely and innovative. The results are likely applicable to the over 1.2 million residents of AL facilities. With the expected rapid growth in ALRs, and the growing trend to include residents with significant care needs and dementia-related behaviors, the project will serve an important role in improving the quality of care provided by staff.