The neuroendocrine control of the hypothalamic-pituitary-gonadal axis is central to human sexual maturation and fertility. To better understand and intervene in human reproductive processes, program members utilize rhesus monkeys as a model system, and the Center for Research in Reproductive Physiology is supported by an NIH program grant in the National Cooperative Research Center program, and it maintains a colony of 350 rhesus monkeys for this work. The control of parturition, mediated by fetal-maternal signaling processes, is a recent area of interest that takes advantage of mouse models.