Alzheimer's disease affects multiple domains of human brain function and has neuropsychological, neuropsychiatric, and neurologic manifestations. Behavioral changes should be assessed as part of a comprehensive evaluation of the effects of cholinergic treatment of Alzheimer's disease. The psychometric properties, origin, source of behavioral information, content, and administration requirements of tools used to assess behavior in Alzheimer's disease affect the type of information garnered and the conclusions that can be derived. Assessment of drug-related behavioral changes can be affected by spontaneous remission of neuropsychiatric symptoms, differing baseline severity of behavioral abnormalities, uncertain magnitude of expected treatment effects, and by the influence of disease stages, concurrent medications, and comorbid conditions. Cholinergic therapies ameliorate behavioral alteration in Alzheimer's disease, and changes in behavior should be monitored when such therapy is initiated.