At any given age, there is wide variation among children in size, physique and body composition, rate of growth, and timing and tempo of biologic maturation.There is corresponding variation among young female athletes. Successful young female athletes are a highly selected group in terms of skill, size and physique, and often socioeconomic status. Comparisons of young female athletes with reference data for the general population indicate that, in general, these young females grow and mature in a similar manner as non-athletes with variation among sports. The short stature and decreased body mass observed in some élite young female athletes likely reflects the selection practice of specific sports. In some of these élite sports there may be a focus on desirable physical and maturational characteristics. It is difficult to attribute the observed variation in the growth and maturation of young athletes to the effects of systematic training. The data presently available do not meet the criteria for causality, and many factors known to influence growth and maturation are usually not considered in studies of young athletes.