Competent authorities seem to agree as to the causes of eye strain in school children other than congenital defects. Standard works on diseases of the eye are practically unanimous in declaring that myopia results from the protracted and unhygienic use of the eyes in near work. Most of the factors tending to cause eye strain exist in the schools. Among them are improper illumination: glare from windows, from glazed paper, and from improperly arranged artificial illumination; improper seating; poor printing and improper type. This bulletin represents the results of a comprehensive survey having for its objects the ascertaining of the following: (1) The nature and extent of defective vision in school children as disclosed by medical inspection; (2) The preventable causes within the schools and factors intimately connected with school life to which may be attributed eye strain and general deterioration of visual capacity, as established by the investigations of different authorities; (3) Efforts made to correct conditions inimical to eyesight in the schools and prophylactic measures adopted; (4) Clinical facilities for the correction of refractive errors and available sources of supplying needy children with eye glasses; and (5) Necessary improvements in facilities and methods in three various fields. The chief considerations were the environmental influences which tend to produce functional disturbances of the eye and thereby to impair the physical fitness of the child for school work and later for industrial or professional work. Eight appendixes present: (1) Book type specimens; (2) School survey forms; (3) Direction for testing sight and hearing; (4) Standard for admission to the conservation of vision classes; (5) Forms used in cooperative health supervision, New York City; (6) English and American specimen forms; (7) Vision test charts; and (8) State laws requiring vision tests. An index and general reference and annotated bibliography are included. Individual sections contain footnotes. (Contains 16 plates.) [Best copy available has been provided.]