The determinants of board structure

Using a comprehensive sample of nearly 7,000 firms from 1990 to 2004, we examine the corporate board structure, trends, and determinants. Guided by recent theoretical work, we find that board structure across firms is consistent with the costs and benefits of the board's monitoring and advising roles. Our models explain as much as 45% of the observed variation in board structure. Further, small and large firms have dramatically different board structures. For example, board size fell in the 1990s for large firms, a trend that reversed at the time of mandated reforms, while board size was relatively flat for small and medium-sized firms.