The present study examined the aerobic, anaerobic and strength performance characteristics of 52 young boys and girls (mean age 10.8 and 11.1 yrs, respectively) on selected laboratory measures. Anthropometrically, the boys and girls were similar, with the exception of measures of body fatness. The boys demonstrated greater values in maximal aerobic power, anaerobic performance, (especially related to body weight), and strength relative to lean body mass. Since body size measures, including height, were similar, the functional differences could not be attributed to such factors. The significant but low correlations between the performance variables failed to support the concept of children as "metabolic non-specialists" as proposed by previous authors. In fact, the large amount of variance not accounted for could be interpreted as supporting the unique contribution of genetic endowment of the effect of habitual activity patterns on the performance measures. Canonical correlations indicated a strong relationship between selected anthropometric and performance variables (rc = .94). For boys, height and weight were strongly related to anaerobic performance, whereas weight and thigh volume were strongly related to all performance measures for the girls.