With the increase of population, the lengthening of the school life of children, and the consolidation of small into large schools, often with many hundreds of children in one building, the care of the health of children while in school becomes correspondingly more important. Since the health of school children depends to a large extent on the location, heating, lighting, ventilation, and other sanitary arrangements of schoolhouses, the laws of States and the regulations of boards of education relating thereto are of great interest and importance to all. This bulletin features the result of a study by Mr. William A. Cook of the University of Colorado on schoolhouse sanitation. It reviews the standards that are set to-day in the different States concerning the physical environment to which the child is entrusted by compulsory attendance upon public schools. The school endeavors to instruct the child how to avoid ills of various sorts; the State, through inspection, is barring from the school those persons who may be a source of danger to others--these are facts that need not at present concern us, though they afford scope for a volume. This bulletin is confined to the hygienic provisions regarding the school site and the school plant. Contents include: (1) Introduction; (2) General control exercised by the State; (3) The school site; (4) The water supply; (5) Toilets; (6) Protect ion against fire and panic; (7) Lighting; (8) Heating; (9) Ventilation; (10) Cleaning and disinfecting; (11) Furniture and equipment; and (12) Miscellaneous. A bibliography is included. Individual sections contain footnotes. (Contains 5 tables.) [Best copy available has been provided.]