Healthy women volunteers between the ages of 45 and 70 who have not had a menstrual period for over a year, are not currently taking hormone replacement therapy, do not smoke and have not had a hysterectomy may be eligible for this study. Candidates will provide a medical history and have a physical examination, including a breast and pelvic exam. They will also provide a blood sample, have a mammogram and pap smear, and be instructed in dietary sources and/or supplements required to be sure they consume at least 1,000 mg. of calcium each day.