The November 2017 negotiations in Bonn, Germany, under the auspices of the United Nations Framework Convention on Climate Change (UNFCCC) validated that the Paris Agreement has met one of two necessary conditions for success. By achieving broad participation, including 195 countries, accounting for 99% of global greenhouse gas (GHG) emissions (1), the agreement dramatically improves on the 14% of global emissions associated with countries acting under the Kyoto Protocol (2), the international agreement it will replace in 2020. But the second necessary condition, adequate collective ambition of the nationally determined contributions (NDCs) that countries have individually pledged, has not been met. One promising approach to incentivize countries to increase ambition over time is to link different climate policies, such that emission reductions in one jurisdiction can be counted toward mitigation commitments of another jurisdiction. Drawing on our research and our experiences in Bonn, we explore options and challenges for facilitating such linkages in light of the considerable heterogeneity that is likely to characterize regional, national, and subnational policy efforts.