Conceptualizing and assessing the effectiveness of transnational forms of governance such as public-private and multistakeholder partnerships, with multiple configurations across different scales and jurisdictions, is a complex task. Evaluating effectiveness requires a counterfactual consideration of what would have been plausible to achieve in the absence of a public-private or multistakeholder partnership, and attempting to establish the pathways through which the partnership has influenced relevant processes, behavior, and outcomes. The problem-solving premise is indeed at the heart of a substantial literature on the effectiveness of formal international institutions and environmental regimes. Individual partnerships are typically embedded in a broader universe of transnational initiatives, formal treaties and domestic policies within a particular context. The ultimate goal of partnerships is to effectively create value for societies by helping to solve often intractable problems they face. Goal attainment is a foundational aspect of partnership effectiveness.