Recent surveys of the condition of the hearing of school children in the United States indicate that more than 3,000,000 have hearing defects. In this paper the detection and the medical handling of these deafened children are discussed, and the results of some extensive tests given. With experienced testers, it is a simple matter to examine children singly, and even the old "watchtick" or "whispered speech" method of testing will yield fairly satisfactory results if each child is tested in a suitable and quiet room. However, testing one by one a large group of children by even these simple methods is very laborious. Some work has been done in several of the large cities by using such methods, but the work went so slowly that it was obviously impracticable to use it in schools generally. The data obtained from these tests showed that a large number of children are deafened,