It would seem superfluous to stress the importance of psychic factors in the causation of enuresis in children. The significance of these factors has been realized for many years and has been emphasized by all who have studied the subject. Only recently this aspect was fully considered by Anderson,1 who reviewed the literature in an exhaustive and admirable manner. The object of the present paper is not to call attention to the psychic factor, but rather to show that this factor is capable of experimental study; in other words, that it can to a large extent be controlled and regulated at will. As far as we are aware, no study of this kind has been reported. It seemed that if a technic of this nature could be established, it would render possible an accurate study of this disturbing disorder and, incidentally, an appraisal of the many pharmacologic and therapeutic agents that are recommended for its cure.This study was carried out in a model institution for child care which harbors children up to 4 years of age, thus affording opportunity for a long period of observation of the physical and mental status both previous and subsequent to our test. The children are kept in a main building which has large, light and well ventilated dormitories as well as in smaller buildings which are equipped with individual glass cubicles. Enuresis has been and is an important problem in this institution, a fact that was brought out strikingly at the beginning of the study when we were able to find only eight children among forty, from 3 to 4 years of age, who did not wet themselves by day or by night. These eight children, seven of whom were boys, were carefully observed in the dormitories during a preliminary period of two weeks so as to be certain that they were absolutely and at all times continent. Some of them were among the brightest in the institution, and as a whole the group may be considered representative of this age period. Before