Healthcare interventions will often affect the lives of carers and patients’ family members. For example, treating symptoms of dementia is likely to reduce strain on family carers, while using out-of-area mental health care is likely to increase anxiety for the patient’s wider family. These ‘family spillovers’ represent potentially important benefits and costs of interventions that are typically neglected in economic evaluation. However, guidelines, from, for example NICE and the US panel on cost-effectiveness, recommend including family spillovers in economic evaluation. This seminar will outline recent research to develop (and apply) methods to do this. It will outline findings from (i) a qualitative study of the impact of patient care on family carers’ lives; (ii) psychometric analysis of the validity of quality of life measures for use with carers in economic evaluation; and (iii) econometric and theoretical work to develop the multiplier approach to combining family spillovers with patient outcomes in economic evaluation.