We hypothesize that, over 3 months, the combination of PTH plus alendronate will, like the combination of PTH plus hormone replacement therapy, result in increments in bone formation exceeding those of bone resorption. We also theorize that this biochemical profile will be reflected in a greater effect on bone mass than during therapy with alendronate alone, when both formation and resorption are elevated. Furthermore, we believe that the changes over the first 3 months can be repeated over additional discrete 3-months cycles after bone turnover returns to baseline.