The six working papers which were prepared for the conference here reported reviewed, in a general way, the pharmacology of the drugs used in psychotherapy, effects on animal behavior, the reported results of clinical studies, their possible public health implications, and the more general problems of the evaluation of the effectiveness of any psychiatric therapy. The first section of the volume consists of these six working papers. Five committees were formed, composed mostly of members of the Committee on Preliminary Screening of Drugs, which thoroughly reviewed current knowledge of the basic mechanisms of action of these psychoactive compounds and, more particularly, the adequacy of available methods for the selection of the test animal and early human screening of compounds of this general sort. Three other committees were originally organized as a group, so that the field of clinical drug evaluation, which was the primary concern of the conference, would receive