Red List criteria for assessing risks to ecosystems are a major global advance in biodiversity conservation. Despite a strong theoretical basis, the criteria are untested. We aim to test their performance under real world constraints, working with partners from state governments and the IUCN. This project is significant because inadequate evaluation frameworks and tools to deal with uncertainties have seriously impeded biodiversity conservation. I will develop and apply a new method, Ecosystem Viability Analysis, and the first performance test for ecosystem assessment. Outcomes include risk assessment guidelines, new analytical tools and scientific publications, providing vital support for a global network of users.