The papers in this volume were presented at the Symposium on Cell Biology of the Uterus held December 12, 1986, on the NIH campus, Bethesda, MD. This was the first of a series of meetings that will be held in con­ junction with the annual meeting of the American Society for Cell Biology. The uterus is now recognized as an extremely complex organ whose nor­ mal function is orchestrated by a delicate procession of cellular and molecular events that investigators are beginning to unravel for the first time. Powerful new analytical methods and the tools of molecular biology are now providing exciting breakthroughs in our basic understanding of uterine structure and function. Thus, the program of this meeting was or­ ganized to cover recent developments in uterine cell biology including the mechanism of hormone action, control of gene expression by nuclear acceptor sites and nuclear receptors, role of growth factors, endometrial cell kine­ tics during the menstrual cycle, regulation of specific protein synthesis and secretion, decidual cell function, and the role of early pregnancy pro­ teins. The material presented in this volume is concerned not only with how hormones and growth factors prepare the endometrium for implantation of the blastocyst, but it also details the recent characterization and identification of specific marker proteins secreted in response to hormone action and early pregnancy.