The paper investigates the relationship between management ownership and corporate performance, measured by Tobin's Q. The authors find that Tobin's Q first increases and then declines as the board of directors' holdings rise. For older firms, there is weak evidence that performance is lower when a firm is run by a member of the founding family compared to when it is run by an officer unrelated to the founder. The study uses a cross-sectional analysis of 371 Fortune 500 firms and employs Tobin's Q and profit rate as performance measures. The results suggest that management ownership between 5% and 20% is associated with the highest performance, while ownership levels below 5% and above 20% are associated with lower performance. The authors also examine the impact of different types of board members (top corporate officers vs. other board members) and the presence of founding families on board performance. The findings support the "convergence of interests" hypothesis at lower ownership levels and the "entrenchment" hypothesis at higher ownership levels. However, the authors acknowledge potential limitations, such as the possibility of spurious correlations and the need for further research on smaller firms and the role of other compensation data.The paper investigates the relationship between management ownership and corporate performance, measured by Tobin's Q. The authors find that Tobin's Q first increases and then declines as the board of directors' holdings rise. For older firms, there is weak evidence that performance is lower when a firm is run by a member of the founding family compared to when it is run by an officer unrelated to the founder. The study uses a cross-sectional analysis of 371 Fortune 500 firms and employs Tobin's Q and profit rate as performance measures. The results suggest that management ownership between 5% and 20% is associated with the highest performance, while ownership levels below 5% and above 20% are associated with lower performance. The authors also examine the impact of different types of board members (top corporate officers vs. other board members) and the presence of founding families on board performance. The findings support the "convergence of interests" hypothesis at lower ownership levels and the "entrenchment" hypothesis at higher ownership levels. However, the authors acknowledge potential limitations, such as the possibility of spurious correlations and the need for further research on smaller firms and the role of other compensation data.