Caryl Rivers and Rosalind C. Barnett are widely acclaimed for their analyses of women, men, and society. In The Truth About Girls and Boys, they tackle a new, troubling trend in the theorizing of gender: that the learning styles, brain development, motivation, cognitive and spatial abilities, and "natural" inclinations of girls and boys are so fundamentally different, they require unique styles of parenting and education.

Ignoring the science that challenges these claims, those who promote such theories make millions while frightening parents and educators into enforcing old...