We describe the development of an Orientation Questionnaire (OQ), a standardized measure of the impairment of an older person's ability to communicate orientation information. Starting with a pool of selected items, we made a series of revisions that resulted in a 17-item questionnaire with a score range from 0 through 40 points. In additional studies we determined that OQ scores evidence adequate reliability (test-retest r = .969) and adequate validity (r with nurse ratings = .798 and .793; r with behavioral assessment = .807). The OQ scores discriminated groups on the basis of environmental structure (community vs. nursing home vs. neuropsychiatric hospital) and psychiatric diagnosis (organic vs. schizophrenic vs. no diagnosis). Tentative classification data are presented, and uses of the OQ are discussed.