Clinical scientists developing rating scales to assess the behavior of patients with dementia have adopted a variety of evaluation strategies. Scales differ according to the source of information (e.g., caregiver versus patient), type of behavior assessed (e.g., mood, agitation, or delusions), origin of the scale (i.e., imported from psychiatry, adapted from psychiatric scales, adapted from scales for neurologic conditions, or developed specifically for dementia), and anticipated application of the tool (e.g., behavioral characterization, longitudinal follow-up, or differential diagnosis). Investigators have rarely articulated the theoretic framework on which their scales are based, and in most cases, theories were eschewed in favor of empirically based assessments of observed behaviors. Theoretic assumptions, however, can be inferred from the structure of the scales.