The problem which is reported in these pages represents an attempt to bring into one work a critical and analytical survey of the material currently available in the field of music therapy. There is such a wealth of new material, especially since the termination of the war, that the necessity for a new and up-to-date compilation of material is evident. The objective of this thesis is to collect general information as to the theory and practices of music therapy, rather than to secure for purposes of statistical analysis great numbers of detailed items in regard to a technique that has not yet been carried to a point where it can be standardized. However, this compilation does include some actual experiments which have been conducted in hospitals with the object of determining the effect on physical and mental patients of certain musical compositions and certain instruments.