The European Holocaust Research Infrastructure’s (EHRI) mission is to overcome widespread dispersal of Holocaust sources. EHRI is an advanced community comprising 23 partners from 17 countries across Europe, Israel and the United States. It is an inter-disciplinary community spanning Holocaust research, archival sciences and the digital humanities. In two previous Integrating Activities, EHRI has integrated an unprecedented amount of information about dispersed Holocaust sources in an online Portal, developed tools to contextualise, analyse and interpret such sources, and set new impulses with regard to inter-disciplinary and trans-national research. EHRI’s past achievements have been recognised, not least by European Strategy Forum on Research Infrastructures (ESFRI) who adopted EHRI on its 2018 Roadmap. The aim of the EHRI-3 project is to move decisively beyond the achieved state-of-the-art. In particular, while EHRI has already integrated the holdings of the major Holocaust RIs, much valuable source material that is held by small local and micro-archives is currently inaccessible to the research communities. EHRI-3 will develop protocols and tools that allow the open up of hidden sources for Holocaust research. EHRI-3 will further enable new trans-national approaches to the study of the Holocaust by developing innovative layers across dispersed sources that connect thematically related, but physically dispersed, collections. It will greatly enhance its access provisions, and integrate new communities – local research and archive networks, universities, researchers working in closely related fields – into its network. Although EHRI is geared towards scholarly communities, the Holocaust is deeply rooted in the development of European societies. EHRI-3 will continue to be a showcase of how a humanities RI can inform societal discourse in areas such as antisemitism, xenophobia, non-discrimination and religious and cultural tolerance.