Three studies were conducted to develop and evaluate a diagnostically based curriculum for disadvantaged preschool children. The population consisted of 139 white and 4 Negro Appalachian 5-year-olds from the lowest socioeconomic class, who scored from 50 to 85 on the 1960 Stanford-Binet L-M Intelligence Scale. One of the 3 groups organized received diagnostic treatment; the second group received traditional kindergarten treatment; the third group received no treatment. A battery of 17 tests and teacher and project-staff evaluations were used for screening, pretest or posttest measurement, diagnosis, or follow-up. The results indicated that the diagnostic curriculum was superior in the areas of intelligence, language, and personal-social adjustment and was equal to the traditional kindergarten approach for motor development. A test schedule, a list of instruments used, and the statistical data are also presented. [Not available in hard copy due to marginal legibility of original document.] (BD)