As part of a multicenter project to study noncognitive behavioral disturbances in dementia, the authors developed a comprehensive caregiver-rated questionnaire for these behaviors. The authors determined the reliability of caregiver ratings and compared caregiver ratings with clinician ratings using standard instruments. Caregivers showed good test/retest reliability for ratings of all types of patient behavioral disturbance. Caregiver interrater reliability was highest for depression and lowest for psychosis. The correlation between caregiver reports and professional assessments was highest for agitation, intermediate for psychosis, and lowest for depression. The match between caregiver and clinician assessments of patient behaviors appears to vary significantly by the type of behavior assessed.