The European Holocaust Research Infrastructure (EHRI) started in October 2010 to build on a network that connects both people (Holocaust researchers, archivists, curators, librarians and digital humanists) and dispersed Holocaust source material and collections. EHRI’s aim is making sources visible in a systematic way in order to counteract the fragmentation of the sources and to reveal interconnections. EHRI focuses on Archive and collection descriptions, which are available through the EHRI Portal. EHRI is currently in its second phase and is on the ESFRI Roadmap2 for a more sustainable future. EHRI has developed a set of controlled vocabularies that serves both as a retrieval and cataloguing tool for the multilingual and highly heterogeneous data of the EHRI portal. These vocabularies were partly implemented in the first phase of the project. In the current phase of EHRI the vocabularies are in the process of quality improvement improve and enrich the existing terms, add new terms, disambiguate and remove the mistakes (deduplication, merging, adding multilingual labels, consistency checks, multiple parent relations, etc.) and increase their coverage. In the EHRI portal the subject terms are currently not available for the public, as they are used only for retrieval purposes.