The risks of bone loss and osteoporosis increase significantly after menopause. Although hormone therapy (HT) can spare menopausal women from bone loss and other menopausal symptoms, Women's Health Initiative (WHI) findings indicate significant potential health risks associated with HT. This has prompted women to switch from HT to naturally occurring compounds similar to estrogen, such as those derived from soy, in the hope that estrogens from plant sources can provide benefits while sparing adverse effects caused by prescribed estrogens. However, the long-term efficacy and safety of plant estrogens are unknown. This study will evaluate the effectiveness of treatment using purified soy isoflavones, a dietary source of phytoestrogens, in preventing bone loss, menopausal symptoms, and other changes associated with estrogen deficiency in young menopausal women. The "Soy Phytoestrogens As Replacement Estrogen (SPARE)" study will provide a foundation of knowledge from which menopausal women and their doctors can begin to make more informed decisions regarding HT and other treatment options.