Childhood and adolescence are time periods characterised by the rapid growth and development of the skeletal system. The timing and magnitude of skeletal development varies considerably between individuals however, environmental factors may make significant contributions to the variance in bone mass. To optimise the development of bone it is important to identify and promote factors that may have a positive effect on bone mass accrual. Two lifestyle factors that may enhance bone mass accural are calcium and exercise. The focus of this thesis was to investigate bone mass accural in children and adolescents and to determine the effect calcium and exercise have on bone mass accural.