This paper presents an assessment of the outcomes of research carried out under the Sustainable Wetlands Adaptation and Mitigation Programme (SWAMP). SWAMP aimed to inform national and international climate policy and practice by developing tools and methods to quantify greenhouse gas (GHG) emissions, carbon stocks and flux in tropical wetlands due to land use, land-use change and forestry (LULUCF). This assessment modelled SWAMP's intended outcomes as a theory of change (ToC) and used qualitative methods to test the ToC and to evaluate whether and how the outcomes were achieved. It found that SWAMP research has helped raise academic and policy interest in wetlands, mangroves and peat forests as carbon reservoirs, and that SWAMP's recommendations informed policy discourse and supported the development of technical guidance and strategies of sustainable wetland management. However, the research had a weak effect on international and Indonesian climate change policies compared to other factors. The Paris Agreement and Indonesia's nationally determined contribution (NDC) do not include the quantification of carbon stocks from mangroves, which are not all located in the forest areas. Knowledge translation was achieved through a variety of mechanisms, with direct engagement identified as particularly important. The outcome evaluation approach proved useful as a way of conceptualising and organising the analysis of research impact on development outcomes.