In this article, the author discusses several research reports demonstrating the existence of sex differences in cognitive function and language skills. Although dozens of studies published in the past five years have demonstrated dramatic sex differences in autonomic function, the educational literature has not emphasized those studies and their potential significance for education. Because girls are hardwired differently from boys, the author explains that single-sex education is the solution to maximize the academic performance of the students. The author explains that single-sex education cannot only improve grades and test scores but it can broaden educational prospects for both girls and boys. The author believes that it is a paradox: coed schools tend to reinforce gender stereotypes, while single-sex schools can break down gender stereotypes. (Contains 17 notes.)