OpenAIRE is the European Union initiative for an Open Access Infrastructure for Research in support of open scholarly communication and access to the research output of European funded projects and open access content from a network of institutional and disciplinary repositories. This article outlines the curation activities conducted in the OpenAIRE infrastructure, which employs a multi-level, multi-targeted approach: the publication and implementation of interoperability guidelines to assist in the local data curation processes, the data curation due to the integration of heterogeneous sources supporting different types of data, the inference of links to accomplish the publication research contextualization and data enrichment, and the end-user metadata curation that allows users to edit the attributes and provide links among the entities.