Purpose. With a sample of cognitively impaired nursing home residents and nursing staff, the following were examined 1) the proportion and nature of aggressive behavior, 2) the frequency and types of aggressive behavior, 3) the difference between the residents who demonstrate aggressive behavior and those who do not demonstrate aggressive behavior (age, mental status, functional status, and pain, length of nursing home stay), and 4) nursing staff responses to aggressive behavior by residents. Methods. A cross-sectional descriptive study design was used. Data were collected from cognitively impaired nursing home residents (N=205) and nursing staff (N=60) at two nursing homes using Ryden Aggression Scale I and II, Mini-Mental State Exam, Modified Barthel Index, Verbal Descriptor Scale, and aggressive behavior management questionnaire. Data were analyzed using descriptive statistics including t-test. Results. About $62.9\%$ residents were found to be aggressive and $38.5\%$ were both physically and verbally aggressive. Pushing, making threatening gestures, hitting, slapping, cursing/obscene/vulgar languages, making verbal threats were occurred frequently. Aggressive residents were significantly older, had more cognitive impairment, had more pain, and stayed longer in the nursing home when compared with non-aggressive residents. Considerable proportion of nursing staff responded to aggressive behaviors inadequately. Conclusion. Aggressive behavior among cognitively impaired nursing home residents is prevalent thus needs to be prevented and reduced. Along with environmental modification, educational programs for nursing staff and family caregivers need to be developed and implemented so that they can have extensive knowledge and skills to manage aggressive behaviors.