Health Technology Assessment is a multidisciplinary process that uses explicit methods to determine the value of a health technology at different points in its lifecycle. Its purpose is to inform decision-making and promote an efficient and equitable health care system. The process is formal, systematic and transparent, and uses state-of-the-art methods to consider the best available evidence about the medical, social, economic, and ethical consequences of using a health technology to determine its value compared to that of existing alternatives. This course introduces the principles of Health Technology Assessment, its historical context, the methodological challenges it presents particularly in terms of value assessment and how they link to decision-making.