Disturbances in mineral and bone metabolism are prevalent in chronic kidney disease (CKD) and an important cause of morbidity, decreased quality of life, and extraskeletal calcification that have been associated with increased cardiovascular mortality. These disturbances have traditionally been termed renal osteodystrophy and classified on the basis of bone biopsy. Kidney Disease: Improving Global Outcomes (KDIGO) recently sponsored a Controversies Conference to evaluate this definition. The recommendations were that (1) the term renal osteodystrophy be used exclusively to define alterations in bone morphology associated with CKD and (2) the term CKD-mineral and bone disorder (CKD-MBD) be used to describe the broader clinical syndrome that develops as a systemic disorder of mineral and bone metabolism as a result of CKD. CKD-MBD is manifested by an abnormality of any one or a combination of the following: laboratory-abnormalities of calcium, phosphorus, PTH, or vitamin D metabolism; bone-changes in bone turnover, mineralization, volume, linear growth, or strength; and calcification-vascular or other soft-tissue calcification. The pathogenesis and clinical manifestations of these components of CKD-MBD are described in detail in this issue of Advances in Chronic Kidney Disease.