Individual and organizational characteristics associated with aggressive behavior among nursing home residents were examined among a sample of 5,494 residents from 23 facilities using the Minimum Data Set 2.0 and the Organizational Social Context scale. On admission, some individual level variables (age, sex, depression, activities of daily life [ADL] impairments, and cognitive impairments) and no organizational level variables were associated with aggressive behaviors. Over time, aggressive behaviors were linked with some individual characteristics (age, sex, and ADL impairments) and several organizational level variables (stressful climates, less rigid cultures, more resistant cultures, geographic location, facility size and staffing patterns). Findings suggest multi-faceted change strategies are needed.