The third meeting of the European Placenta Group and the Rochester Trophoblast Conference in 1989 was concerned with placental communication; this volume presents selected contributions from the meeting, in four thematic sections: Growth, Differentiation, and Establishment of Pregnancy; Signals which regulate Placental Gonadotropin and Lactogen Secretion; Trophoblastic Signal Mechanisms, and Signals and Placental Vasculature.