Turner syndrome is associated with short stature, multiple physical stigmata, absent pubertal development, and increased learning problems. This study is designed to (1) examine the effects of sex steroids (androgen and estrogen) on multiple variables including growth rate, GH binding protein, IGF-I, IGFBP3, and cognitive function in the setting of supplemental growth hormone administration and (2) to investigate any synergistic or additive effects of the androgen and estrogen combination versus each alone, on the above variables.