Although much of the care of Alzheimer disease (AD) patients and their families is carried out by health professionals who are not specialists in AD or geriatrics, little is known about how knowledgeable these health professionals are about AD. An AD knowledge test was constructed through careful instrument development procedures and then administered through a mail survey. Subjects were 693 individuals, including experts in AD care, generalist health care professionals (primary care physicians, psychologists, social workers, and nurses), nursing students, hospital staff nurses, and assorted health professionals. A 12-item scale with excellent psychometric properties was developed. Experts in AD care performed significantly better than generalist health care professionals on all items. All four groups of generalist health care professionals showed important deficits in fundamental knowledge about AD; for example, only 40% of generalists (vs. 97% of experts) knew that AD is the most common cause of severe memory loss in people over age 65. Results suggest that, although knowledge about assessment and management of AD has increased and has been widely disseminated, many health care professionals remain uninformed about AD. Suggestions for professional education and for use of the UAB AD Knowledge Test for Health Professionals are discussed.