The purpose of this study is to survey the development trends of school libraries in the western world namely U. S. A., Canada by analyzing such items as education and environment, staff, policy, standard and professional organization, and to find out how and why they were able to maintain efficient library services. The major findings are summarized as follows : (1) There are school district supervisor whose functions are to direct and supervise the school libraries in the district. (2) The school district supervisor, school administrator, Teacher and Teacher librarian all recognize the importance of its educational role and cooperate together for the development. (3) They gether statistical data on school library for continuous revision of statement, guideline and standard. (4) Not only the educational organization and the library organization but also the private foundation conduct systematic research and extend financial aid for the development of school library. (5) The Compulsory Codes and pertinent laws have been enacted to promote school library development.