Purpose: In an attempt to more thoroughly describe aggressive behavior in nursing home residents with dementia, we examined background and proximal factors as guided by the Need-Driven Dementia-Compromised Behavior model. Design and Methods: We used a multivariate cross-sectional survey with repeated measures; participants resided in nine randomly selected nursing homes within four midwestern counties. The Minimum Data Set (with verification by caregivers) identified participants. We used a disproportionate probability sample of 107 participants (51% with a history of aggressive behavior) to ensure variability. Videotaped care events included four of direct care (shower baths, meals, dressing, and undressing) and two of nondirect care (two randomly selected 20-minute time periods in the afternoon and evening). The majority of participants (75%) received three shower baths, for a total of 282 videotaped baths. Results: Because the shower bath was the only care event significantly related to aggressive behavior (F = 6.9, p less than 0.001), only those data are presented. Multilevel statistical modeling identified background factors (gender, mental status score, and lifelong history of less agreeableness) and a proximal factor (amount of nighttime sleep) as significant predictors (p less than 0.05) of aggressive behavior during the shower bath. We found significant correlations between aggressive behavior and negative subject affect (r = 0.27) during the bath, and aggressive behavior and lifetime agreeableness level (r = -0.192). We also found significant correlations between mental status and the amount of education (r = 0.212), and between negative caregiver affect and negative participant affect (r = 0.321). Implications: We identified three background and one proximal factor as significant risk factors for aggressive behavior in dementia. Data identify not only those persons most at risk for aggressive behavior during care, but also the care event most associated with aggressive behavior. Together these data inform both caregiving for persons with dementia as well as the design of intervention studies for aggressive behavior in dementia.