A COMPARATIVE, LONGITUDINAL STUDY WAS CONDUCTED TO EXAMINE SPECIFIC PERFORMANCE CHARACTERISTICS OF DEAF AND NORMAL CHILDREN ON SELECTED COGNITIVE TASKS. THE SAMPLE, DISTRIBUTED INTO 3 AGE CATEGORIES, CONSISTED OF 72 NORMAL AND 60 DEAF CHILDREN. MEASURES WERE SELECTED TO ASSESS THE PERFORMANCE OF SUBJECTS (1) IN DIFFERENT AREAS OF COGNITION, (2) BY LANGUAGE AND NONLANGUAGE TECHNIQUES, (3) ON INFORMATION ACQUIRED INCIDENTALLY OR PROVIDED IN A TESTING SITUATION, AND (4) WITH MEASURES THAT WERE SUITABLE FOR ADMINISTRATION TO BOTH LEARNING AND DEAF SUBJECTS. CONSERVATION TASKS (PIAGET) WERE ADMINISTERED. SEVERAL VOCABULARY MEASURES FOR ASSESSING COMMON WORD USAGE AND UNDERSTANDING WERE ALSO ADMINISTERED. ALL TESTS WERE ADMINISTERED TO EACH AGE GROUP OF NORMAL CHILDREN. WHEN REQUIRED, TESTS OF NONLANGUAGE RESPONSES WERE ADMINISTERED TO THE DEAF SUBJECTS. SYSTEMATIC ANALYSES WERE EMPLOYED TO COMPARE LONGITUDINAL CHANGES, CROSS-SECTIONAL AGE DIFFERENCES, SEX DIFFERENCES, AND RESIDENT VERSUS DAY SCHOOL DIFFERENCES (APPLICABLE ONLY TO THE DEAF CHILDREN). FINDINGS OF THESE ANALYSES SUGGESTED THAT (1) DEAF SUBJECTS TEND TO SHOW LESS INCREMENTAL LEARNING THAN NORMAL SUBJECTS, (2) DEAF SUBJECTS TEND TO VARY MORE THAN NORMAL SUBJECTS ON THE LEVEL OF THEIR PERFORMANCES AMONG DIFFERENT TESTS, AND (3) THE PERFORMANCES OF DEAF SUBJECTS, AS THEIR AGES INCREASE, TEND MORE TO MATCH AND SOMETIMES SURPASS THE PERFORMANCES OF NORMAL SUBJECTS. FURTHER RESEARCH WAS RECOMMENDED TO STUDY THE ENVIRONMENTAL FACTORS WHICH RELATE TO COGNITIVE PERFORMANCES OF THE DEAF. (RS)