The Healthy Female Birth Control Study is looking for women ages 24–44 with a healthy BMI (under 26). Participants must be on birth control or willing to use it, and cannot have had their appendix or gallbladder removed. The study involves a screening, 5 days of pill use, 1 full-day visit in San Dimas, and 4 follow-up visits (about a week apart). Screening takes place in Rialto, and the study lasts about 2 months.