Growing Up In Digital Europe (GUIDE) is Europe’s first comparative longitudinal birth cohort survey, which will be an essential evidence base for child wellbeing policy-making across the UK and Europe for decades to come. It will provide data on a representative sample of babies and children from most European countries, following them up to the age of 24. This will make GUIDE one of the largest European social science Research Infrastructures. GUIDE was included on the 2021 iteration of the European Strategy Forum on Research Infrastructures Roadmap in recognition of its importance for the future. The GUIDE project is set to continue up until the 2050s when the younger cohort will be aged 24. The research design of GUIDE is centered on an accelerated cohort structure, with the first cohort being 8-year-olds and the second cohort being 9-month-old babies. Nationally representative samples of respondents from participating countries will be used with sufficiently large numbers to be able to cope with anticipated attrition rates. The research instruments are input harmonized to facilitate comparative analysis and the fieldwork processes are common for all participating countries. The questionnaire content for the first waves of data collection focuses on the participants’ demographic and socio-economic context, as well as family life, parenting and psychological measures, for the main career questionnaires and general family life, feelings, wellbeing, and educational measures for the 8-year-olds. Subsequent data collection waves will include a range of repeated measures and new measures.