Longitudinal research seminar took place The Scottish Universities Insight Institute, Glasgow, on the 20th and 21st of April 2011. The intention was to identify the core constituents of a robust longitudinal design that would be fit for the evaluation of the efficacy of everyday professional intervention aimed at improving the lives of vulnerable children. The intention was also to explore the type and range of data that is required to capture fundamental aspects of everyday multi-professional intervention and child well-being. On the basis of this we identify the most appropriate measures to capture intervention and child well-being and develop a robust analytical package for capturing outcomes over the short, medium and longer term. Key issues for longitudinal research design: lessons from Growing Up in Scotland (GUS) . Paul Bradshaw, Scottish Centre for Social Research