It is the object of this series of monographs to present the experiments and interpre­ tations of a given laboratory. We have attempted in this volume to present our view of receptor-steroid interactions and their relation to steroid-induced responses. This view is necessarily biased by our own experimental results. While we have tried to in­ clude the views and results of others, this volume is not meant to be comprehensive. Rather it is selective and examines those topics within the general field of steroid hor­ mone action which we have addressed at the laboratory bench. The work reviewed in this volume would not exist without the help and support of many associates. Our mentors included Jorge Awapara, Jack Gorski, Henry Komer, Bill Ray, and Mike Zarrow. Associates instrumental in this work include George Barr, John Burgner, Sam Campbell, Constance Cardasis, Hitkan Eriksson, Stan Glasser, Jim Hardin, Mohammed Kalimi, Bruce Lester, Barry Markavarich, Shirley McCormick, Tony Means, Dan Medina, Ann Miller, Bert O'Malley, Helen Padyku­ la, Zigmund Paszko, Dale Snow, Susan Upchurch and Marian Walters. Students who have contributed to this effort include John Anderson, Joe DeLibero, Aaron Hsueh, Katrina Kelner, Debbie Metzger, Randy Richards, Jim Schaeffer, Mike Tytell, Lane von Brunt, and Cheryl Watson. Technicians without whose assistance this work could not exist include Toni Cetti, Wendy D'Attilio, Jeanie Haselby, Lily Hsueh, Helen Hyland, Jim Kovar, Kathy O'Connor, and Peggy Sansone.