In this fact-driven book, Doreen Kimura provides an intelligible overview of what is known about the neural and hormonal bases of sex differences in behavior, particularly differences in cognitive ability. Kimura argues that women and men differ not only in physical attributes and reproductive function, but also in how they solve common problems.

She offers evidence that the effects of sex hormones on brain organization occur so early in life that, from the start, the environment is acting on differently wired brains in girls and boys. She presents various behavioral, neurological, and endocrinological studies that shed light on the processes giving rise to these sex differences in the brain.