The Shipley-Hartford Retreat Test was designed as an aid in detecting mild degrees of intellectual deterioration in individuals of dull normal or higher original intelligence. The test consists of 2 parts, a vocabulary test and an abstractions test. Performance on the multiple-choice vocabulary test can be used as an approximation of "original" intelligence because vocabulary ability is less resistant to change than the ability to do abstract thinking, and because vocabulary performance correlates more highly with general tests of intelligence than does performance on any other single test. The abstractions test consists of unfinished problems. The subject must supply the abstract principle necessary to complete each of them. The ability to think in abstract terms is much more likely to "be disturbed by psycopathological or organic brain disorders than is vocabulary ability. Intellectual impairment is measured by this test by the extent to which an individual''s abstract thinking falls short of his vocabulary. The deficit is expressed in a convenient ratio, the CQ (conceptual quotient) . The subjects studied in this report were 977 neuropsychiatric patients of an average age of 27 years (range 17 to 64 years). The average level of educational achievement was 10th grade, with 70% of the group going beyond elementary school, and 1/3 going beyond high school. Scores were available for 134 of these patients on the Wechsler-Bellevue Test for general intelligence. The results on the vocabulary section of the Shipley-Hartford Test indicated that 74.5% of the group were of average or above average intelligence, and compared well with the Wechsler-Bellevue estimate of 75% of the normal adult population. In contrast to this, the total score estimate on the Shipley-Hartford Test indicated that only 53% of the group were functioning at that level of intelligence. In the vocabulary section of the test, 13% were characterized as being of borderline intelligence or mentally deficient; yet, on the basis of total score (vocabulary plus abstractions), more than twice that number (32%) were "functioning" at such a low level. In all a large proportion (62%) of the neuropsychiatric cases showed a lowering of efficiency, or a deterioration, in their intellectual functioning.