We experimentally investigate the distribution of children's time preferences along gender and racial lines. Black boys have significantly larger discount rates than any other demographic group. Discount rates among Black girls are comparable to rates among White girls. Although White boys exhibit higher discount rates than girls, the difference is small and not statistically significant. These results are robust to alternative measures of patience and to regression analyses that control for socio-economic background and school performance. The measured differences in discount rates are large. All things equal, a Black boy requires expected returns to education 13-15% higher than Black girls to compensate for his larger discounting of future payoffs. Equally importantly, we show that impatience, as measured by discount rates, has a direct effect on behavior. An increase of one standard deviation in the discount rate increases by 5 percent the probability that a child incurs at least 3 school-related disciplinary actions. This result suggests that experiments capture new and relevant information on children. Overall, our results suggests that time preferences might play a large role in setting appropriate incentives for children. Understanding the factors behind these differences in preferences is an important area for future research.