The critical role of growth factors in normal as well as abnormal cellular growth and function has become overwhelmingly apparent in recent years. The significant advances in reproductive biology within this rapidly expanding field were highlighted at the Serono Symposia, USA, symposium entitled Growth Factors in Reproduc­ tion. The conference focused on growth factors as polyfunctional regulators of growth and development in the reproductive system. The program was organized into five areas: (1) growth factors as polyfunctional regulators of growth and development, (2) growth factors and gonadal function, (3) regulation of normal and neoplastic mammary growth, (4) regulatory peptides in reproductive tract development and function, and (5) embryo-maternal signaling. This volume constitutes the contributions ofthe invited symposium speakers and is organized into sections representing the five topic areas of the sessions. Drs. Eli Y. Adashi, Robert B. Dickson, David C. Lee, James Hammond, John A. McLachlan, and R. Michael Roberts, who served as chairmen ofthese sessions, not only provided invaluable advice and assistance in organizing the symposium, but contributed significantly to its content. The enthusiasm and esprit de corps of the poster presenters and discussion participants also helped make this symposium succeed as the first of its kind. Finally, special thanks are due Drs. James Posillico and Lisa Kern ofSerono Symposia, USA, for their guidance and support in the conception and planning of the symposium and in the publication of this volume.