In this review, recent studies on the etiology and pathogenesis of Paget's disease, with particular attention to the apparent familial clustering of cases and the possibility of a causal role for viral infection, are discussed. The role of biochemical markers of bone turnover is explored, as well as the value of imaging in confirming the diagnosis, monitoring the effects of therapy, and assessing complications. The bisphosphonates are widely used in the treatment of Paget's disease; experience with newer, more potent second- and third-generation bisphosphonates, as well as potential future roles for calcitonin, are described. Studies on some of the orthopedic effects of Paget's disease are also presented.