Recent global initiatives in ecosystem restoration offer an unprecedented opportunity to improve biodiversity conservation and human health and well-being. Ecosystems form a core component of biodiversity. They provide humans with multiple benefits – a stable climate and breathable air; water, food and materials; and protection from disaster and disease. Ecosystem restoration, as defined by the UN Decade on Ecosystem Restoration, includes a range of management interventions that aim to reduce impacts on and assist in the recovery of ecosystems that have been damaged, degraded or destroyed. This Guide promotes 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.