importancT and interest, it was judned to bo an appropriate focus, con-sideritiK the primary purposes to he accomplished hy the hook. Somewhat more than 1,000 separate titles were reviewed and abstracted. These do not by any means constitute all of the available literature, nor were all of them eventually used in the writing of the volume, which is frankly interpretive. However, it is hoped that the material on which the volume eventually was based does constitute a sufficient cross-section of the literature that no important concepts have been omitted.Many persons have contributed to the completion of this effort. Many of the concepts leading to recognition of the implicit exchange between superordina«.? and subordinates in formal organizations were developed hy Dr. Carl J. Lange, who was among the first members of the Human Resources Research Organization to study leadership. His work, which began in 1954, initiated a series of studies of leadership that has continued within HumRRO until the present time. Further, though no longer a part of HumRRO, Dr. Lange contributed materially to the thinking in the present work hy reviewing the manuscript and providing many helpful suggestions.It would be difficult within limited space to recognize the many other persons who also contributed to the completion of the work.