Public policymaking and implementation in the United States are increasingly handled through local, consensus-seeking partnerships involving most affected stakeholders. This paper formalizes the concept of a stakeholder partnership, and proposes techniques for using interviews, surveys, and documents to measure each of six evaluation criteria. Then the criteria are applied to 44 watershed partnerships in California and Washington. The data suggest that each criterion makes a unique contribution to the overall evaluation, and together the criteria reflect a range of partnership goals--both short-term and long-term, substantive and instrumental. Success takes time--frequently about 48 months to achieve major milestones, such as formal agreements and implementation of restoration, education, or monitoring projects. Stakeholders perceive that their partnerships have been most effective at addressing local problems and at addressing serious problems--not just uncontroversial issues, as previously hypothesized. On the other hand, they perceive that partnerships have occasionally aggravated problems involving the economy, regulation, and threats to property rights. (Contains 4 tables, 7 figures and 14 footnotes.)