Children have distinct nutritional needs relative to growth. Adequate intakes of energy and essential amino acids are necessary for optimal deposition of lean body mass and normal growth in young children. However, there are limited data concerning protein needs of children. Most recommendations for children represent an interpolation of data derived from infants and adults. Indeed, current protein requirements for young children, while scientifically based, are estimates at best. Historically, protein status in children was evaluated using classic nitrogen balance protocols. This work indicates that a wide range of protein intakes (0.6-2.9 g/kg) can be considered adequate for young, growing children. The ability of nitrogen balance studies to accurately reflect protein utilization has been examined and it appears that further investigations of protein utilization in children using stable isotope methodology, as well as traditional nitrogen balance protocols, are necessary to better evaluate protein needs of growing children. In addition, protein source may be an important factor in optimal diet design for growing children.