Rickets and osteomalacia are disorders of bone that are a result of insufficient levels of vitamin D. This vitamin is essential for adequate mineralization of bone. Therefore, deficiency of vitamin D results in soft and fragile bones. This deficiency is one of the most important rickets and osteomalacia causes. Rickets affects children and osteomalacia affects adults. These bone diseases are relatively uncommon in the United States because they can be easily prevented by ensuring adequate vitamin D in the body. However, understanding these diseases is important because children and adults who develop rickets and osteomalacia suffer devastating consequences.