This is a 2-year study that will compare the effects of denosumab and risedronate in people who are taking glucocorticoid therapy. The study will look at bone mineral density (BMD) at the spine and hip during two years of treatment. Other endpoints will include changes in wrist characteristics measured by QCT, satisfaction with treatment, effects on biochemical markers of bone turnover (blood tests that can measure bone health), fracture rates, and effects on bone histology (characteristics of bone that can be studied under a microscope).