Open-air schools represent one of the latest developments in public-school organization. They came as the result of a desire for better conservation of the health of those children who, by reason of a tuberculous affection, poor nourishment, or other debilitating conditions, were unable to profit physically and mentally by the life and work of regular indoor schools. This method of dealing with physically defective children signalizes one of the most interesting and decided changes undertaken in school management for many centuries. Open-air schools are based on the conception that the first essential to a worthy education is sound bodily health. They have grown out of a new emphasis on the value of health and physical soundness and recently discovered facts bearing on the nature of certain diseases and the best methods of protecting human life from the possible effects of these diseases. The chief purposes of this bulletin are to record something of the history and progress of the open-air school movement, to point out some of the results which have been attained through this means of dealing with delicate school children, to designate in some detail the programs followed in such schools, and to bring together in a convenient form other information which may be needed by those who are planning to organize and equip schools of this character. Appended to this document are the following: (1) Social, economic, and hygienic conditions of 886 families of 1,062 open-air school pupils in 15 American cities; (2) Estimated expense of equipping and maintaining an open-window room with full regime of medical and nursing service, feeding, and rest; (3) Recipes for open-air schools; (4) List of Chicago menus, materials used, and their cost; (5) Suggestions for open-air classes; (6) Legislation and committee recommendations; and (7) Lists of open-air schools. (Contains 19 footnotes, 104 figures, 13 forms, an index, and a selected bibliography.) [Best copy available has been provided.]