This guide was developed to promote the application of the science of ecosystem risk assessment, which involves measuring the risk of ecosystem collapse, in ecosystem restoration. It explores how the IUCN Red List of Ecosystems and ecosystem restoration can be jointly deployed to reduce risk of ecosystem collapse. The Red List of Ecosystems assesses the risk of collapse based on five criteria: A) change in ecosystem distribution; B) restricted distribution; degradation of C) the abiotic environment, or D) biotic processes; and E) the probability of ecosystem collapse estimated using a quantitative model. Ecosystems are placed in easy-to-understand categories of relative risk ranging from Least Concern, to Critically Endangered, and ultimately, Collapsed.