THE CHARACTERISTIC ABILITIES AND ACHIEVEMENT IN READING AND OTHER RELATED SKILLS AND UNDERSTANDINGS OF ELEMENTARY SCHOOL CHILDREN WHO HAD ACCESS TO CENTRALIZED LIBRARY SERVICES WERE COMPARED WITH THOSE WHO DID NOT. DATA WERE GATHERED FROM SIX SCHOOLS WITH VARYING SCHOOL LIBRARY PROVISIONS WHICH INCLUDED EXAMPLES OF--(1) A CENTRALIZED SCHOOL LIBRARY WITH A QUALIFIED SCHOOL LIBRARIAN AND A COLLECTION MEETING HIGH QUANTITATIVE AND QUALITATIVE STANDARDS, (2) CLASSROOM COLLECTION OF BOOKS BUT NO CENTRALIZED LIBRARY, AND (3) A CENTRALIZED COLLECTION OF BOOKS NOT ATTENDED BY A QUALIFIED LIBRARIAN. MEASURES WERE DEVELOPED AND APPLIED TO SUCH AREAS AS--(1) THE PROVISION OF LIBRARY-RELATED MATERIALS, (2) THE ACCESSIBILITY OF RESOURCES AND SERVICES, (3) THE EXTENT OF LIBRARY-RELATED ACTIVITIES, (4) THE DEGREE OF MASTERY OF LIBRARY SKILLS, AND (5) THE AMOUNT AND KIND OF READING DONE BY CHILDREN. SCORES WERE STUDIED IN TERMS OF--(1) THEIR RELATIONSHIP TO MEASURES OF EDUCATIONAL ACHIEVEMENT OF SIXTH-GRADE CHILDREN AND SOCIOECONOMIC STATUS OF PARENTS AND (2) THEIR ABILITY TO DIFFERENTIATE BETWEEN SCHOOLS HAVING VARYING CATEGORIES OF LIBRARY PROVISION. THE MEASURES DIFFERENTIATED IN FAVOR OF THE SCHOOL LIBRARY CATEGORY IN MOST, THOUGH NOT ALL, CASES FOR THE SAMPLE. (TC)