The corpus luteum (CL) is one of the few endocrine glands that forms from the remains of another organ and whose function and survival are limited in scope and time. The CL is the site of rapid remodeling, growth, differentiation and death of cells originating from granulosa, theca, capillaries, and fibroblasts. The apparent raison d'etre of the CL is the production of progesterone and all the structural and functional features of this gland are geared toward this end. Because of its unique importance for successful pregnancies, the mammals have evolved a complex series of check and balances that maintains progesterone at appropriate levels throughout gestation. The formation, maintenance, regression, and steroidogenesis of the CL are among the most significant and closely regulated events in mammalian reproduction. During pregnancy, the CL's fate depends on the interplay of ovarian, pituitary and placental regulators. At the end of its lifespan, the CL undergoes a process of regression leading to its disappearance from the ovary and allowing the initiation of a new cycle. The generation of transgenic, knock-out and knock-in mice and the development of innovative technologies have revealed a novel role of several molecules in the reprogramming the granulosa cells into luteal cells and in the hormonal and molecular control of the function and demise of the CL. The current review highlights our knowledge on these key molecular events in rodents.