This paper explores cross-sectional differences in the behavior and performance of mutual fund managers. Using data on fund managers' characteristics, such as age, SAT scores, and MBA status, the authors find that younger managers and those from higher SAT schools tend to achieve higher returns. These differences are attributed to both systematic differences in expense ratios and risk-taking behavior, as well as performance differences. The study also examines the labor market for mutual fund managers, finding that managerial turnover is more performance-sensitive for younger managers. The authors find that managers from higher SAT schools have higher risk-adjusted excess returns and that MBAs tend to outperform non-MBA managers. However, when controlling for differences in systematic risk, the superior performance of MBAs is largely explained by their higher risk-taking. The study also finds that younger managers are more likely to be replaced after a poor year, suggesting that performance is a key factor in managerial turnover. The paper also investigates whether differences in managerial characteristics explain performance differences. It finds that managers with different characteristics tend to work for funds with different expense ratios, risk profiles, and investment styles. For example, high-SAT managers tend to hold higher beta portfolios, while MBAs are more likely to invest in "glamour" stocks. The study also finds that younger managers are more likely to be replaced after a poor year, indicating that performance is a key factor in managerial turnover. The authors conclude that some mutual fund managers are indeed better than others, as evidenced by their superior performance. This finding is consistent with the idea that mutual fund managers are informationally efficient, as they gather and analyze information in an asset market that is only nearly efficient. The study also finds that funds managed by managers from higher SAT schools and younger managers tend to outperform others, even after controlling for expenses and other factors. The results suggest that some funds may be expected to beat the market after expenses, providing a potential justification for the effort consumers expend in choosing between funds.This paper explores cross-sectional differences in the behavior and performance of mutual fund managers. Using data on fund managers' characteristics, such as age, SAT scores, and MBA status, the authors find that younger managers and those from higher SAT schools tend to achieve higher returns. These differences are attributed to both systematic differences in expense ratios and risk-taking behavior, as well as performance differences. The study also examines the labor market for mutual fund managers, finding that managerial turnover is more performance-sensitive for younger managers. The authors find that managers from higher SAT schools have higher risk-adjusted excess returns and that MBAs tend to outperform non-MBA managers. However, when controlling for differences in systematic risk, the superior performance of MBAs is largely explained by their higher risk-taking. The study also finds that younger managers are more likely to be replaced after a poor year, suggesting that performance is a key factor in managerial turnover. The paper also investigates whether differences in managerial characteristics explain performance differences. It finds that managers with different characteristics tend to work for funds with different expense ratios, risk profiles, and investment styles. For example, high-SAT managers tend to hold higher beta portfolios, while MBAs are more likely to invest in "glamour" stocks. The study also finds that younger managers are more likely to be replaced after a poor year, indicating that performance is a key factor in managerial turnover. The authors conclude that some mutual fund managers are indeed better than others, as evidenced by their superior performance. This finding is consistent with the idea that mutual fund managers are informationally efficient, as they gather and analyze information in an asset market that is only nearly efficient. The study also finds that funds managed by managers from higher SAT schools and younger managers tend to outperform others, even after controlling for expenses and other factors. The results suggest that some funds may be expected to beat the market after expenses, providing a potential justification for the effort consumers expend in choosing between funds.