This volume contains the proceedings of the Symposium on Molecular and Cellular Aspects of Periimplantation Processes, held July 15 - 18, 1994, in Boston, Massachusetts. Despite considerable research, the molecular and cellular bases of embryo-uterine interactions are still poorly understood. The papers included in this volume address recent advances in several areas in the field of implantation, including uterine receptivity, hormonal regulation, cell-cell interaction, growth factors/cytokines, immunobiology, and trophoblast invasion.