Abstract. The poster presents the background, conceptual framework, methodology and initial results of a mixed research project, investigating information practice and user requirements of historians, humanities scholars and social scientists working on the Holocaust. The results of the study will be a foundation for the specification of functionalities of the European digital infrastructure planned as part of the EU-funded European Holocaust Research Infrastructure project, and consisting of the EHRI search/portal and the EHRI Virtual Research Environment. Particular issues to be dealt with are the summarization of qualitative evidence from semi-open interviews by means of a conceptualization of relevant descriptive codes of research activities, resource types and tools/services; identification of specific user requirements and of different researcher profiles through statistical analysis of an online questionnaire defined on the basis of initial qualitative research; and, identification and theorization of special needs of Holocaust research, seen as a highly multi- and inter-disciplinary field of inquiry.