THIS STUDY WAS DESIGNED TO TEST HYPOTHESES THAT LIBRARY SCHOOL GRADUATES AS BOOK SELECTORS FOR PUBLIC LIBRARY COLLECTIONS ARE SUPERIOR TO UNTRAINED LIBRARIANS. A STUDY WAS MADE OF LIBRARY STANDARDS AND LIBRARY LITERATURE IN ORDER TO ESTABLISH GENERALLY ACCEPTED PRINCIPLES WHICH RESULT IN BUILDING GOOD LIBRARY COLLECTIONS. TWO GROUPS OF TEN LIBRARIANS EACH WERE STUDIED, ONE COMPOSED OF LIBRARY SCHOOL GRADUATES AND THE OTHER UNTRAINED LIBRARIANS. ALL WERE EMPLOYED IN SMALL PUBLIC LIBRARIES AND SELECTED ALL THE BOOKS ADDED TO THE ADULT COLLECTIONS. THE LIBRARIES WERE VISITED, THE LIBRARIANS INTERVIEWED, AND A 5 PER CENT SAMPLE OF 1965 ADULT BOOK PURCHASES WAS DRAWN. IT WAS DISCOVERED THAT LIBRARY SCHOOL GRADUATES--(1) USED A SIGNIFICANTLY GREATER NUMBER OF BOOK SELECTION AIDS, (2) SELECTED BOOKS OF HIGHER QUALITY, (3) ACQUIRED FEWER GENERAL BOOKS FROM SALESMEN, BOOK CLUBS, OR COMMERCIAL LENDING AGENCIES, AND (4) DID SOMEWHAT BETTER IN MAKING WELL-ROUNDED SELECTIONS IN VARIOUS SUBJECT AREAS. LITTLE DIFFERENCE WAS FOUND BETWEEN THE TWO GROUPS IN THE AREA OF CONTROVERSIAL BOOKS. OTHER TESTS SHOWED THAT YEARS OF LIBRARY EXPERIENCE WERE RELATED LESS STRONGLY TO SUCCESS THAN LIBRARY SCHOOL EDUCATION AND THAT GRADUATES OF TYPE I LIBRARY SCHOOLS USUALLY PERFORMED CONSIDERABLY BETTER THAN OTHER GRADUATES. THE FACT THAT LIBRARY SCHOOL GRADUATES DID SOMEWHAT BETTER THAN THE UNTRAINED LIBRARIANS ON MOST OF THE MEASUREMENTS USED SUPPORTS THE THEORY THAT THERE ARE REAL, BUT NOT LARGE, DIFFERENCES BETWEEN LIBRARY SCHOOL GRADUATES AND UNTRAINED LIBRARIANS IN BOOK SELECTION COMPETENCE. THIS REPORT IS AN ABRIDGEMENT OF A UNIVERSITY OF ILLINOIS PH.D. DISSERTATION WITH THE SAME TITLE, AVAILABLE FROM UNIVERSITY MICROFILMS, BOX 1346, ANN ARBOR, MICHIGAN 48106, ORDER NUMBER 67-6675, $3.60 FOR MICROFILM, $12.60 FOR XEROGRAPHY, 279 PAGES. (JB)