The understanding of skeletal physiology has advanced rapidly in the last 15 years, particularly in the growing organism, where complex interactions have been found to control bone growth, modelling and remodelling. Many heritable congenital and acquired abnormalities interfere with these processes and are the causes of structural and metabolic bone diseases. If there is complexity at the basic level, there is also complexity at the clinical level. This monograph provides a detailed description of paediatric bone diseases, concentrating on abnormal conditions.