This article empirically tests the hypothesis that cooperative boards of directors and board size, specifically, can influence firm performance. Most existing studies of cooperative governance rely on qualitative data to draw inferences; however, this chapter uses several USDA data sets and a survey of co-op managers to determine whether above-average board size has a negative impact on co-op performance. This approach is comparable to those found in the corporate governance literature; however, it contributes to the cooperative literature by providing statistically-based findings on optimal board size. Specifically, this study finds that additional board members do eventually reduce some measures of performance; however, board size must be quite large.