Results obtained from phases I and II of the Rosetta stone project for body composition (BC) in White, Black and Asian adults have shown that measurements of BC are strongly influenced by age, sex, race, and choice of method. Also, the traditional methods for measuring BC based on the assumed constants of potassium, water, or density of the fat free mass, give erroneous results because these "constants" vary by sex, age, race and health status. Studying fatness by applying complementary techniques orthogonal to one another, we have developed translation tables between the traditional and new methods. We have also studied anthropometrics and BIA, as surrogate methods for field uses, and we have mapped the compartmental relationships of fat and the f at free body as functions of aging in healthy adults. These results have been used as norms for the interpretation of BC measurements in patients with AIDS, obesity, paraplegia and aging. A similar study for children and adolescents is needed. We propose to perform our standard BC measurements: total body potassium, water, dual photon absorptiometry, bioimpedance analysis, electrical capacitance, anthropometry and underwater weighing, in White, Black and Asian children aged 6 to 18 years, an extension of our previous studies in adults. We shall generate standards based on sex, age, race and pubertal stage for body fat, fat free mass, bone mineral and density, and other derived descriptors of BC will be extended. We shall develop translation tables between methods and validate surrogate methods for children as we have for adults. A second and compelling motive for extending these studies to children is to enhance the quality of clinical care and the underlying research applications from which pediatricians and their patients may benefit. Our summary publication for the completed study of approximately 2000 volunteer adults and the 1170 studies in children and adolescents this project will add will be designed to serve workers in nutrition, physiology, pediatrics, aging, and the other research communities where body composition parameters are required.