¹This article is the first of a series of publications from the authors' treatment research program at U.C.L.A. on childhood gender problems, supported by United States Public Health Service Research Grant 21803 01A1 from the National Institute of Mental Health. The essentials of this article were presented in a paper entitled, “Behavioral Treatment and Assessment of Childhood Cross-Gender Problems”, presented by the authors at the Fifty-third Annual Convention of the Western Psychological Association at Anaheim, California, on April 13, 1973. The authors express their appreciation to Thomas Farrell, Alfred Lauck, Mitchell Taubman, Hannelore Wilhelm, Thomas Willis, and Cindy Yates for their assistance in data collection, and to Richard Green, M.D., Neuropsychiatric Institute, U.C.L.A., for referring the first treatment cases to us. This manuscript was written while Dr. Rekers held a Postdoctoral Fellowship in clinical psychology from the Foundation's Fund for Research in Psychiatry. A portion of this study was based upon a dissertation (Rekers, unpublished) submitted by the first author to the Department of Psychology, the University of California at Los Angeles, in partial fulfillment of the requirements for the Ph.D. degree. Reprints may be obtained from either author, U.C.L.A. Psychology Department, 405 Hilgard Avenue, Los Angeles, California 90024.