The likely future global climate regime, based on nationally determined, non-legally binding commitments, is not by itself likely to produce emissions reductions sufficient to prevent dangerous climate change. There is, however, already significant mitigation occurring outside the context of the UNFCCC that could potentially be scaled up to fill the gap. This chapter, expanding on earlier work, proposes a building block strategy that focuses on incubating and scaling up multilateral and multi-stakeholder initiatives in discrete sectors with mitigation potential. It outlines three paradigms – clubs, linkage and dominant actor – that provide a conceptual and institutional framework for mobilising non-climate interests of actors in order to generate associated climate benefits. Finally, it suggests that recent institutional developments in the UNFCCC could be used as a platform to launch and enhance these non-UNFCCC initiatives, compatible with the emerging UNFCCC strategy.