Drawing from theories of regime interplay and social learning, this article investigates linkages between hybrid governance schemes and intergovernmental regimes. My analytic framework suggests that, by enhancing cooperation among stakeholders, transnational public-private partnerships will facilitate policy-makers’ learning, and accordingly advance the formation of intergovernmental regimes. Here I use qualitative methods to examine the influence of the UNEP Global Mercury Partnership on negotiations over different components of the Minamata Convention on Mercury. Technical and scientific information provided by this partnership helped relevant policy-makers understand the problems to be addressed and some appropriate solutions, thereby accelerating the consensus-making process and shaping the features of certain provisions. I also compare the influences of different partnership areas, revealing that inclusive stakeholder engagement and boundary coordination between different governance schemes are two important conditions for transnational partnerships to promote cooperation in intergovernmental fora.