This report presents an achievable methodology for the Red List assessment of European habitats in terrestrial, freshwater and marine realms, outlines a process that will deliver such evaluations and gives an indication of resources needed. It shows how the EUNIS habitat classification can be employed as an assessment typology, recommends criteria for quantity and quality, assessment of the past trend and current state, and advises including supplementary information on drivers, threats and restorability. The report recommends thresholds and assessment categories that are fully compatible with developing IUCN proposals. As a basis for its recommendations, the report reviews the kinds of typology that are used for habitat description – classifications based on fine-scale species assemblages, mid-scale habitat/biotope classifications and broad-scale ecosystem typologies. It reviews how far each typology has been used for Red List assessment and discusses the various scales on which such evaluations have been made. Relationships between these typologies and classifications used in the Habitats Directive and Marine Strategy Framework Directive are discussed. The report then outlines the core criteria and the thresholds that have been used so far for Red List assessment: quantity (Area of Occupancy, Extent of Occurrence, dispersal/fragmentation, endemism and stand size), quality (speciesrichness, presence of rare, threatened or endemic species, structure, function & landscape context) and trends (in both quantity and quality, both back in time and forwards). It also considers various supplementary criteria that have been used for some Red List assessments: scales of naturalness/hemeroby, drivers and threats, degrees of resilience and restoration capacity. Actual Red List evaluation processes are then described, in the developing IUCN programme for ecosystems and among other approaches, and the role of expert judgment and peer review in assessment is discussed. There is then a critical review of the assessment categories employed for Red Listing: extinct (completely destroyed, extirpated), critically endangered (immediately threatened, severely declined), endangered (threatened, significantly declined), vulnerable (potentially endangered), least concern (secure, not endangered), increasing and data-deficient. The report outlines some of the major data sources available to inform expert judgement: vegetation plot data for terrestrial and freshwater habitats, the Map of the Natural Vegetation of Europe, other terrestrial maps, marine data sources and the Article 17 reporting database. It then outlines relationships between Red List assessment and ecosystem services. The report provides an assessment Fact Sheet and provides two Case Studies which outline available data, deficiencies of information and feasibility of assessment. Finally, there is a comprehensive bibliography of all references.