Dementia is a debilitating and increasingly pervasive condition impacting cognitive decline across the globe. Behavioral and psychological symptoms of dementia (BPSD) impact quality of life (QoL) for people with dementia and are key interventional targets. Pharmacological interventions for BPSD can be costly, ineffective or life-threatening prompting law makers and the Federal Drug Administration (FDA) to support non-pharmacological interventions like multi-sensory environments (MSE) as the preferred first line of treatment. Despite this support for non-pharmacological interventions like MSE, there has been inconsistency in evaluative methodologies and application of MSE interventions, impeding the widespread use of MSE in dementia-care settings. Therefore, there is a critical need for empirical investigation of well-defined MSE in non-pharmacological dementia-care. The purpose of this study is to investigate the impact of MSE on aggression/agitation during assisted bathing, showering and/or tub bathing for veterans with dementia. The VA has implemented MSE therapy for veterans with dementia since 2010 and the impact of MSE on aggression remains to be evaluated. In 2013, due to favorable initial results, the VA installed both fixed-room and mobile cart MSE applications in 53 VA community living centers (CLCs) across the US, including one in Lake City, Florida which received mobile MSE carts and waterproof MSE equipment for use during assisted bathing, showering, and/or tub bathing. Most acts of aggression/agitation for people with dementia occur during assisted bathing and there is a strong need for evidence-based research of non-pharmacological interventions to reduce problem behaviors, decrease healthcare provider burden and improve quality of life (QoL) for people with dementia. The overall goal of this study is to investigate the effectiveness of MSE in the reduction of agitation/aggression during assisted bathing, showering, and/or tub bathing for veterans with dementia.