Clubs, defined as smaller groups of countries that take action outside of the United Nations Framework Convention on Climate Change (UNFCCC), have been suggested in the literature as a way forward for climate action. Some have suggested them as a replacement of the UNFCCC. This article, by contrast, explores how clubs could assist in catalyzing greater ambition, defined as emissions reduction targets in line with climate science, which would eventually be captured in the UNFCCC. An analysis of the existing climate club landscape shows that clubs currently promote dialogue and/or implementation of specific activities. While these clubs make important contributions, their mandate and configuration are not focused on significantly increasing ambition. Current clubs enable incremental, rather than transformational change. An analysis of selected proposals for new kinds of climate clubs shows that, as a common element, they call for further incentives for action to underpin greater ambition. The article further analyzes a set of incentives, predominantly economic, for ‘transformational clubs’, related to trade, investment, labour mobility or access to finance, and identifies a set of future research questions.