This article fills a gap in both the public management and human resources literatures by applying a conceptual model supported by a criteria-based evaluative framework to assess and compare the nature and capacity of city government human resources management systems. Various management reforms have stwept through many American governments recently, but practitioners and researchers have not reflected carefully on how these reforms contribute to management effectiveness. One management system that has received relatively little systematic attention is human resources management. The existing research about assessing human resources is sparse, focuses on the private sector, and fails to converge upon a set of criteria for evaluating human resources management systems comprehensively. In earlier work, we proposed a theory that dissects the black box of government management to identify key management systems and define their contribution to management capacity and to overall government performance. In this article, we refine this model by developing a set of criteria that serve as indicators of the effectiveness of human resources management systems. We apply our analysis that measures human resources management capacity and controls for two key environmental contingencies: unionization and government structure. We find that higher capacity governments are able toa chieve better human resources out-comes, and that more unionized governments and those that lack a senior professional administrative officer generally have lower human resources management capacity