Are African Americans really better at basketball than Caucasians? Are blonds really dumber than brunettes? Are women really worse at math than men? The short answer is yes. The longer answer is no. Let me explain by focusing on the stereotype that women can’t do math. At first glance, this stereotype seems to be true. For instance, men continue to outperform women on the math sections of the SAT and GRE, and men outnumber women in college math courses and math-related jobs. Surely this is evidence that women are not as good at math as men. But as this article will explain stereotypes are self-perpetuating and not only reflect but also cause performance differences between groups.