I have considered the neural organization of the system responsible for pulsatile LH and GnRH secretion and have described the feedback actions of two ovarian steroids, estradiol and progesterone. These steroidal feedbacks are complex: They are time and dose dependent; they include both inductive and inhibitory effects; they reflect actions at multiple sites within the hypothalamo-hypophyseal axis. In this review we emphasized two ovarian steroids especially important to this regulatory system and observations in females of two species that have been particularly well studied in this regard. This emphasis required exclusion of excellent studies in other species, with other steroids, and in the other sex. This focus, however, permitted a more detailed evaluation of current concepts in an area of fundamental importance to the neuroendocrine regulation of reproduction.