This is a mechanistic cellular investigation of human peritoneal fluid, tissue and primary, subject-derived cell cultures to evaluate hormones, cytokines and growth factors involved in endometrial cell dysfunction associated with endometriosis. Women undergoing indicated surgical laparoscopy will be recruited. At the time of their procedure, pelvic fluid will be sampled, the eutopic (intrauterine) endometrium will be biopsied using a silastic catheter (Pipelle) and when available, portions of extirpated pathological samples will be de-identified, assigned endometriosis stage (or control if no endometriosis is noted) and transported to the laboratory. Primary cell cultures will be generated using established methods. Differential responsiveness of the cell cultures from endometriosis subjects vs. controls will be assessed.