Because of the individual authority of each State for its own educational program, practices and policies differ widely among them in many respects. Yet in the midst of differences there are also common elements of development. The U. S. Office of Education, in presenting this series of monographs, has attempted to point out those common elements, to analyze the differences, and to present significant factors in State educational structure. In so doing, it accedes to the requests of a large number of correspondents who are students of State school administration and who have experienced the need for the type of material offered in this series. This monograph aims to give a general overview of State supervision for the improvement of instruction for the United States, the staff organization employed for the purpose within State departments of education, the objectives set up by the staff, and the procedures followed for attaining them. The growth in State supervisory staffs, the parallel developments in supervisory practice, with trends in both, are also discussed, with some comments and conclusions based on the study as a whole. Four appendices present: (1) Distribution of State supervisors by special fields, States, and years; (2) Distribution of State supervisors by special subjects, States, and years; (3) Representative publications of State departments of education concerning instruction, by States; and (4) Charts showing organization of supervisory staffs, by States. Individual chapters contain footnotes. [Best copy available has been provided.]