Many persons engaged in the institutional and in-service training of teachers have come to realize that the selection, guidance, training, and evaluation of teachers must be put upon a more substantial basis. The purpose of this investigation is to throw light, if possible, upon the quali ties essential to success in teaching, the means of identifying these quali ties in specific persons and situations, and the changes that may take place in them with training. More specifically the study attempts to answer the following questions: (1) What are the qualities essential to success in teaching, particularly for teachers of the social studies in the 7th and 8th grades of rural schools in Wisconsin? (2) How valid and reliable are certain instruments commonly employed in the measurement of teaching ability? And (3) what changes may be made in the quali ties ordinarily considered essential to success in teaching through train ing, particularly through the training of teachers in service? Besides these more specific purposes, it is hoped that this investigation may throw light upon the nature and organization of human abilities in general as exemplified in teaching. There are many other important problems in this field but those here enumerated seemed most appropriate to the conditions under which the investigation was conducted.