Although some argue that tokenism drives the selection of female directors, we show that they have a significant impact on measures of board effectiveness. In a large panel of data on publicly-traded firms from 1996-2003, we find that (1) the likelihood that a female director has attendance problems is 0.29 lower than for a male director, (2) male directors have fewer attendance problems the greater the fraction of female directors on the board, (3) firms with more diverse boards provide their directors with more payperformance incentives, and (4) firms with more diverse boards have more board meetings. We also show that the positive relationship between corporate performance measures and gender diversity documented by previous studies is not robust to attempts to address the endogeneity of diversity. Instead, the average effect of gender diversity on both market valuation and operating performance appears to be negative. This negative effect is driven by companies with greater shareholder rights. In firms with weaker shareholder rights, gender diversity has positive effects. Our results suggest that diverse boards are tougher monitors. Nevertheless, mandating gender quotas in the boardroom may not increase board effectiveness on average, but may reduce it for well-governed firms where additional monitoring is counterproductive.JEL classification: G30; G34; J16

We analyze the consequences of the board's dual role as advisor as well as monitor of management. Given this dual role, the CEO faces a trade-off in disclosing information to the board: If he reveals his information, he receives better advice; however, an informed board will also monitor him more intensively. Since an independent board is a tougher monitor, the CEO may be reluctant to share information with it. Thus, management-friendly boards can be optimal. Using the insights from the model, we analyze the differences between sole and dual board systems. We highlight several policy implications of our analysis.

We argue in this paper that executives can only impact firm outcomes if they have influence over crucial decisions. Based on this idea we develop and test a hypothesis about how CEOs' power to influence decisions will affect firm performance: since managers' opinions may differ, firms whose CEOs have more decision-making power should experience more variability in firm performance. Thus performance depends on the interaction between executive characteristics and organizational variables. By focusing on this interaction we are able to use firm-level characteristics to test predictions that are related to unobservable managerial characteristics. Using such firmlevel characteristics of the Executive Office we develop a proxy for the CEO's power to influence decisions and provide evidence consistent with our hypothesis. Firm performance (measured by Tobin's Q, stock returns and ROA) is significantly more variable for firms with greater values of our proxy for CEO influence power. The results are robust across various tests designed to detect differences in variability.

This paper is a survey of the literature on boards of directors, with an emphasis on research done subsequent to the Hermalin and Weisbach ( These questions are fundamentally intertwined, which complicates the study of boards due to the joint endogeneity of makeup and actions. A focus of this survey is on how the literature, theoretical as well as empirically, deals-or on occasions fails to deal-with this complication. We suggest that many studies of boards can best be interpreted as joint statements about both the director-selection process and the effect of board composition on board actions and firm performance. * The authors wish to thank Ji-Woong Chung, Rüdiger Fahlenbach, and Eliezer Fich for helpful comments on earlier drafts.

The representation of women in top corporate officer positions is steadily increasing. However, little is known about the impact this will have. A large literature documents that women are different from men in their choices and in their preferences, but most of this literature relies on samples of college students or workers at lower levels in the corporate hierarchy. If women must be like men to break the glass ceiling, we might expect gender differences to disappear among top executives. In contrast, using a large survey of all directors of publicly-traded corporations in Sweden, we show that female and male directors differ systematically in their core values and risk attitudes. While certain population gender differences disappear at the director level, others do not. Consistent with the findings for the Swedish population, female directors are more benevolent and universally concerned, but less power-oriented than men. However, they are less traditional and security-oriented than their male counterparts. Furthermore, female directors are slightly more risk-loving than male directors. This suggests that having a women on the board need not lead to more risk-averse decision-making.