This contribution will trace some of the many seminal studies on the female uterus (endometrium) over the centuries and conclude with a description of some current research initiatives in our laboratory. Numerous contributions from many investigators over the years have contributed to our current understanding of endometrial function. The historical section of this chapter is intended to be a brief overall description of some of these efforts and not exhaustive. Additional information can be found in the review articles and books cited herein.