This session looks at the concept of ‘science capital’ – science-related qualifications, knowledge, literacy and social contacts, which were developed in the ASPIRES project to help understand patterns in young people’s science aspirations. We explain the concept of science capital and how it relates to participation in informal science learning (ISL). We discuss how science capital might be measured (to help assess the effectiveness of interventions and out-of-school ISL experiences) and explore which elements of science capital may be more (or less) amenable to intervention. Illustrations are provided from the Enterprising Science project which seeks to build science capital with students, teachers and families.