S4Fashion is empowering small medium-sized enterprises to introduce new sustainable and circular economy products, services, methods, tools, and business models for the fashion industry. We aim to identify and amplify the best and up to date practices for a greener fashion sector. The project, throughout its three-year life cycle, will produce new evidence-based knowledge on sustainability and circular economy for the fashion industry and share its findings with the whole ecosystem of the European fashion community. S4Fashion is cofounded by the COSME program of the European Union. S4Fashion supports, connects, and empowers 25 transnational partnerships to work collaboratively for the creation of sustainability solutions for the fashion industry. The 25 pilot projects benefit from a bespoke program including mentoring, networking opportunities, and financial support. Beyond the pilot projects, a much larger number of organizations is supported through a parallel program of workshops and training activities building a system of transnational sustainable fashion laboratories for the testing and measurement of new methodologies. Our vision is to influence the European fashion community to change perspectives and redefine the fashion sector responding to the needs of our time for ethical, inclusive, and responsible production and consumption. We want to create a space where the whole European fashion ecosystem can innovate, collaborate and share knowledge during and beyond the lifecycle of the project.