A study of 2,702 children in schools for the blind in the school year 1933-1934 disclosed certain facts concerning the causes of blindness and the possibilities for preventive work that made it seem desirable to direct the attention of ophthalmologists to the eye conditions incident in the younger age groups. This paper is presented in the hope that the dissemination of the information secured may make it possible to obtain more reliable data which will stimulate medical research and programs for the prevention of blindness. Reliable information on causes of blindness has been lacking. Even when detailed studies have been made they have been limited to a comparatively small number of patients or to a restricted geographic area, so that they could not be considered representative; and because the methods and classifications used lacked uniformity, the results of these studies could neither be compared nor totaled scientifically. Recognizing this difficulty,