The Specific Aim of this project is to compare the efficacy and cost-effectiveness of continuous oral contraceptives versus leuprolide/norethindrone in the treatment of endometriosis-associated chronic pelvic pain. This comparison will be based on a randomized, double-blind, trial of women with chronic pelvic pain who have been diagnosed with endometriosis at the time of surgery within the last 3 years. We hypothesize that, over a 12-month period of postoperative treatment, the efficacy of oral contraceptives is no worse than leuprolide/norethindrone, and that treatment with oral contraceptives is more cost-effective.