One of the EU's most important visions is to create a much more sustainable society, supported by smart development and sustainability indicators to measure progress. Although previous EU projects have created powerful tools to investigate sustainability and further its application, more work is still needed. The EU-funded project 'Synergies in multiscale interlinkages of ecosocial systems' (SMILE) aimed to improve on existing tools to analyse different dimensions of sustainability and further its application. In particular, the project looked at the interlinkages among different economic, social and environmental aspects and objectives. It juxtaposed these against policymaking, supported by the input of different stakeholders to advance scientific sustainability research. The project also examined trade-offs and synergies existing between the different objectives related to sustainable development, based on accepted sustainability indicators. The most important achievement of SMILE was the development of a toolkit to further its objectives, with partners conducting case studies to assess its viability in different socioeconomic, environmental and cultural contexts. These case studies were conducted in Spain, Italy, Romania, Finland and the United Kingdom, as well as in Laos to understand different key sustainability topics (e.g. forestry, agriculture, farming). Supported by these revealing case studies, the toolkit is capable of rapidly producing information about unsustainable trends. In the meantime, the project has produced policy recommendations to improve sustainability conditions at various geographical scales. It has also identified pivotal factors in promoting stakeholder involvement, including governmental agencies, industrial organisations and citizen groups. Overall, the SMILE toolkit outlines three key approaches to analysing sustainability. The data and results emerging from SMILE can build on past projects and future initiatives to further sustainability research, rethinking the topic and creating better policies in this respect. This should bring a welcome boost to sustainable development.