ATRIUM brings together 30 partners from 12 countries, including four major European research infrastructures (RIs) — DARIAH, ARIADNE, CLARIN, and OPERAS — to strengthen the foundations of arts and humanities (A&H) research across Europe. The project tackles long-standing structural barriers in the RI landscape: fragmented access to resources, uneven interoperability, reproducibility gaps, undervaluation of non-traditional research outputs, and persistent inequalities across regions and languages. Funded by the European Commission, ATRIUM addresses these challenges through an integrated service and software catalogue, a catalogue of reusable workflows, an assessment framework for non-traditional research outputs aligned with the Coalition for Advancing Research Assessment (CoARA), and a transnational access (TNA) programme that expands skills and participation. To ensure that Europe can maintain an open, diverse and globally competitive A&H research ecosystem, this Policy Brief, aimed at European Union (EU) and national policymakers, research funders and research infrastructure leaders, proposes seven policy recommendations.