The purpose of this study was to establish normative data for untrained, healthy North American children by means of the James protocol for bicycle ergometry. Data were obtained on 151 of 185 children (70 girls and 81 boys). Their ages ranged from 7 years 6 months to 12 years 9 months. All subjects were divided into groups by gender and body surface area (BSA). Maximum heart rates were greater in girls. The mean difference between maximum and recovery heart rates differed significantly by gender, girls taking longer to recover than boys. Maximum oxygen consumption (measured in cubic centimeters per minute per kilogram body weight) did not differ in boys and girls. Ventilatory anaerobic threshold (VAT) occurred when there was an isolated increase in the slope for ventilatory equivalent for oxygen consumption (VE/VO2) with no change in the slope for ventilatory equivalent for carbon dioxide production (VE/VCO2) when both were plotted against time. Absolute oxygen consumption (VO2) at VAT increased with BSA in both sexes, and, when normalized to body size and expressed as a percent of VO2 maximum, no significant difference was observed between the sexes. These data may be used in the fitness evaluations of preadolescent children from North America.