The vision of the Confederation of Open Access Repositories (COAR) is a sustainable, global knowledge commons based on a network of open access digital repositories. In order to realize this vision, COAR works to align policies, standards and practices across the repository community. Part of this work involves semantic interoperability across repositories and repository networks. The COAR Interest Group “Controlled Vocabularies for Repository Assets” is developing a set of controlled vocabularies for the bibliographic metadata elements used describing research outputs. Controlled vocabularies offer a uniform standard terminology for describing content, and assist with resource discovery, sharing and reuse of metadata and content, as well as integration between different systems. This helps systems to inter-operate and become compliant with the open science principles. COAR is promoting the adoption of the vocabularies by the repository community in order to improve interoperability across systems, organizations and regions. To that end, COAR has been working with the most common repository software platforms to have the vocabularies integrated directly into their workflows. The adoption of COAR Vocabularies is also encouraged in international and national guidelines for repository and CRIS managers such as the OpenAIRE Content Provider Guidelines, LA Referencia Guidelines and the German DINI Certificate for repositories. The COAR Vocabularies are also integrated and referenced in value added services like the the Phaidra Classification Server of University of Vienna in Austria, and Research Vocabularies Australia operated by the Australian National Data Service (ANDS). Harmonization of vocabulary terms with the CASRAI dictionaries and glossaries is an ongoing task. So far the COAR Controlled Vocabularies Interest Group has released two vocabularies: Resource Types, to identify the genre of a scholarly output and Access Rights, to declare its degree of openness. A third vocabulary about Version Types is now under review. These vocabularies are designed to be multilingual and currently support 14 languages. The vocabularies are implemented in the web standard SKOS and released for public reuse under Creative Commons CC BY 4.0 license. For more information visit the COAR website of the group: https://www.coar-repositories.org/activities/repository-interoperability/coar-vocabularies/