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.

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