Ecosystem-based approaches for adaptation (EbA) integrate the use of biodiversity and ecosystem services into an overall strategy for helping people adapt to climate change. To date, insight into these approaches has often been based on reports from isolated anecdotal case studies. Although these are informative, and provide evidence that people are using ecosystems to adapt, they provide rather limited insight in terms of measuring and evaluating the effectiveness of ecosystem-based adaptation, especially when compared with technical or structural adaptation interventions. The body of scientific evidence indicating how effective such approaches are is lacking in some aspects. Where evidence does exist it is often dispersed across a range of related fields, such as Natural resource management, disaster risk reduction and agroecology. To date, there has been little attempt to systematically assemble and analyse this evidence. Therefore, the current state of evidence regarding the merits or otherwise of ecosystem-based adaptation is unknown and it has not been possible to identify prevailing knowledge gaps to inform research and analysis, which will enable policymakers to compare ecosystem-based adaptation with other adaptation options. Methods: This protocol details the methodology to be used to conduct a systematic map of peer-reviewed published journal papers and a limited selection of grey literature, to give a methodical overview of the state of the evidence base for ecosystem-based adaptation effectiveness, and to identify the current knowledge gaps. It addresses the following question: What is the state of the evidence base regarding the ability of ecosystem-based approaches for adaptation to help people adapt to the impacts of climate change?