The European Commission has identified the challenge of population ageing as the most pressing policy issue in the 21st century. As Europeans live longer and disabilities in this population increase, valid and comparable longitudinal data on their health is essential for evidence based policy making. Valid data requires better measurement instruments and methodologies for longitudinal and cross-population comparative analyses. After an in-depth critique of existing ageing studies, COURAGE in Europe will develop, and validate in three countries, measures of health and health-related outcomes for an ageing population. These measures will be grounded in the WHO’s International Classification of Functioning, Disability and Health (ICF). The ICF offers the only scientifically valid framework for evidence-based measurement of non-fatal health outcomes. We also propose to disentangle the confusion found in current ageing studies between objective states of health and subjective conditions of quality of life and well-being. These elements must be measured independently and against the background of the clear conceptual framework of health. COURAGE in Europe will enhance the scientific study of ageing by developing a tool to demonstrate the relevance to the ageing population of two environmental factors: the built environment and social networks. In sum, COURAGE in Europe is not proposing another ageing study, but the development of a tool to measure of health and health-related outcomes, for an ageing population, that offers objective and evidence-based prevalence trends, and which relates these to both quality of life and well-being outcomes as well as to the role of health determinants such as the built environment and social networks. Understanding ageing and its determinants will have a considerable impact on public health policies by identifying strategies for intervention.