Experiments in collaborative governance over the last several decades have transformed the way the public's business is getting done. Despite growing interest, empirical research on the performance of cross-boundary collaboration continues to be limited by conceptual and methodological challenges. This article extends previous research to develop a performance matrix for assessing the productivity of collaborative governance regimes (CGRs). Three performance levels (actions, outcomes, and adaptation) are addressed at three units of analysis (participant organizations, the CGR itself, and target goals), creating a performance matrix of nine critical dimensions of CGR productivity. This performance matrix is illustrated with a case study of a CGR operating on the U.S.-Mexico border.