Ecosystem-based adaptation (Eba) uses biodiversity and ecosystem services as part of a larger adaptation strategy to climate change. While the conservation and sustainable development community considers EbA to be a strong method of addressing climate change and its associated challenges, there is still a tendency for policy makers to implement traditional engineering solutions for adaptation, rather than investing in EbA. The need for solid data on the cost-effectiveness of this nature-based approach was the driver behind an IUCN study identifying the economic costs and benefits associated with EbA. The study reviewed projects and assessed existing data from Costa Rica, India, Mexico, Peru, the Philippines and Tanzania. The results show that there are still extensive knowledge gaps, and that further cost-benefit analysis work and field evidence is required to showcase more clearly the nature-based solutions that EbA offers to climate change.