The purposes of this study were: (1) to compare the Wechsler Intelligence Scale for Children (WISC) and the Wechsler Preschool and Primary Scale of Intelligence (WPPSI) as measures of individual intelligence of beginning first graders; (2) to determine the relationship of Verbal, Performance, and Full Scale IQ's of both tests to end-of-year reading achievement; (3) to determine if poor readers manifest any distinctive subtest patterns; and (4) to identify combinations of subtests from two group readiness tests and the IQ tests that best predict reading achievement for boys, for girls, and for the total group. Fifty children, evenly divided by sex, were tested. Some of the conclusions were: (1) the WISC and WPPSI are statistically equivalent measures of mental ability for beginning first graders; (2) poor readers do not exhibit marked deficiencies in specific aspects of tested intelligence, but good readers exhibit a proficiency on WISC and WPPSI arithmetic subtests; (3) verbal abilities appear to be better predictors than performance abilities for both boys and girls; and (4) the best predictors for the total group seem to be a knowledge of the environment and how to deal with it, a knowledge of letter names and initial consonant sounds, and an ability to use mathematical concepts. (Author/TO)