Maximizing calcium retention by the skeleton within the genetic potential is a key strategy to prevent osteoporosis. It has been shown that calcium retention varies between blacks and whites and between gender within race. This study is designed to study the relationship between calcium intakes and calcium retention in Asian adolescent girls and boys. It is hypothesized that calcium intakes which maximize calcium retention will be lower in Asians than for whites studies under the same conditions. In addition it is thought that the differences between races in the physiological mechanisms involved in calcium metabolism will result in a lower calcium intake required to observe a plateau in calcium retention. This is turn could be translated into lower calcium requirements in Asians relative to Caucasians for achieving optimal peak bone mass.