In an increasingly sustainable business environment, start-ups go through the complex process of adopting sustainable practices while maintaining their lightness and capacity for innovation. In an attempt, specific projects can provide a more accurate method of assessing the extent to which these start-ups are helping to address their social and environmental issues. The need for such an approach becomes even more relevant in a context in which the focus on sustainability is constantly growing and in which start-ups struggle to find effective ways of assessing and communicating the specific impact of projects in the absence of appropriate tools. For these reasons, the main objective of the research was to develop and draw on an in-depth methodological examination that can support project-based social and environmental impact assessments that foster informed choices and sustainable continuous learning processes for companies.