School libraries are indispensable adjuncts to education, a base for generating innovative thinking, a stimulus to culture, and an aid to individual self-development. The IFLA/UNESCO School Library Manifesto, the qualitative standard for universal provision, recommends that for each Country there should be work on developing links between the school's objectives and its library's service. The Manifesto strongly endorses the creation of strong and effective school libraries. The national school library systems in Germany, Iran and Turkey have provided information services over the years, yet inadequate study to evaluate these services has limited understanding of the effects of the Manifesto. This study examined the impact of the Manifesto through literature analysis, visiting 425 school libraries in these countries and/or using their websites, interviews with 1107 individuals, and a summative comparative evaluation. The results reveal that the national implementations of the Manifesto, its statements on objectives and duties, are a valuable support to ongoing processes of policy formulation. The study also shows evaluations from the librarians' own perspectives, and uncovers general suggestions for more efficient and effective Solutions. The comparisons completed in 2008 reveal important information about the impact of the Manifesto in school library services, and enable recommendations to be made for the future use and development of the Manifesto.