Abstract Increasing evidence suggests that early-life conditions may have substantial consequences on individual health and wellbeing throughout the lifecycle. Development of complex social and health issues may be best understood through longitudinal studies that combine the perspectives of social and health sciences. Future Finland aims to collect a nationwide lifelong data resource that through collaborative multidisciplinary research will strengthen future population welfare. Future Finland will be based on index children born in Finland (43.000/year) during a specific time period. National registers and other administrative data sources will provide data for the age cohort (children), their parents and siblings, with special effort on data from more rarely used sources (e.g., electronic health records, school records). Subsets of cohort members will be recruited in early pregnancy (consent) to undergo deeper data collection through questionnaires, biological and environmental samples and measurements, and digital monitoring data (e.g., physical activity, citizens digital footprint). The Future Finland preparatory phase started in 2023 at the Finnish Institute for Health and Welfare (THL). The Future Finland design and focus areas are currently being planned based on identified information gaps and with consultations of experts from other birth cohort studies. Data collection is planned to start in 2025 by piloting and foreseen to expand to full-scale in 2027-2028. The Future Finland data resource will be made available for the entire research community as openly as possible, at the same time maintaining the highest possible data security standards to protect privacy now and in the future. Future Finland enables novel interdisciplinary research and intervention setups, which will strengthen the knowledge base for societal decision-making and promote the future population welfare. Future Finland is funded by the Finnish Cultural Foundation. Key messages • Future Finland initiative will collect a nationwide lifelong data resource enabling novel cross-disciplinary research designs to produce groundbreaking and impactful scientific results. • A larger-scale use of data enables novel interdisciplinary research and intervention setups strengthening the knowledge base for societal decision-making and promoting the future population welfare.