This chapter describes the strategies of monitoring and selecting ovarian stimulation protocols, all aiming at optimizing in vitro fertilization (IVF) outcomes. The aggregate of the history, physical exam, antral follicle count (AFC) and hormonal assays predicts a good or poor responder and should be the basis of designing an initial IVF protocol. Once an individual is deemed a good responder, the focus of stimulation is judicious administration of an initial gonadotropin dose to mitigate the risk of ovarian hyperstimulation syndrome (OHSS). Gonadotropin-releasing hormone (GnRH) antagonist protocols have been increasingly applied to good responders due to their added advantage of diminishing the risk of OHSS. The timing of human chorionic gonadotropin (hCG) injection should be individualized based on several factors, including follicle diameter, serum estradiol (E2) level, prior cycle response, and embryo quality within the context of the particular controlled ovarian hyperstimulation (COH) protocol.