Countries are not on track to meet the 2030 Agenda for Sustainable Development that comprises 17 Sustainable Development Goals (SDGs) and 169 targets to be achieved by 2030. Although SDGs aim to shift the world onto a sustainable and resilient path, countries are not yet able to make transformative changes for long-term sustainability that require building social prosperity and foundations within planetary boundaries. Failing to achieve SDGs will negatively affect billions of people and worsen environmental conditions and socio-economic problems. Therefore, BeyondSDG aims to understand the necessary conditions for long-term sustainability, including achieving SDGs, based on the following specific objectives: identify critical targets for prioritizing SDGs; investigate the effects of (under)achieving SDGs on long-term sustainability beyond 2030; and identify sustainability targets for the post-2030 development agenda. For this, BeyondSDG applies a threefold scientific approach that combines statistical analysis of empirical and modelled data, qualitative analysis of literature, and knowledge co-creation with stakeholders, including sectoral experts and policymakers, based on systems thinking. This combination of three approaches is complementary and essential to deal with the complex topic of long-term sustainability.