These two volumes on Estrogens, Progestins, and Their Antagonists repre sent a thematic extension of the series, Hormones in Health and Disease. The first publication in the series, Steroid Hormone Receptors: Basic and Clinical Aspects, focused on recent advances in the anatomy of steroid receptors and members of the steroid receptor superfamily. Consistent with the spirit of the series, the authors addressed issues of clinical significance of steroid receptor detection in hormone-related disorders. The second volume in the series, Hormones and Cancer, attempted a more direct examination of ac tions of hormones in cancerous tissues and cells. In these two volumes, which together form the third in the series, the editor, Dr. Edward Pavlik, has introduced a team of leading investigators engaged in research on various aspects of the steroids that regulate female reproductive physiology. Estrogens and progestins, the main components of the most widely used contraceptive pills, have found a variety of uses in clinical endocrinology. These volumes contain discussions that range from the introduction of novel hormonal ligands to hormonal antagonism by steroid analogs. A balanced treatment is provided of applications of the steroids in treatment and management of hormone-dependent conditions and malignancies. The remarkable synthesis of literature contained in this volume will provide a reader with both the fundamental concepts underly ing steroid hormone physiology and the clinical applications of observations made on basic aspects of hormone action. I congratulate the editorial leadership of Dr.