The Competency Matrix is a core project deliverable that describes Open Science skills of research library staff. It is based on the Open Science Ecosystem, presented in the DI4R abstract [File 1.2] and poster [File 1.3], and on insights from the literature review [File 2.1]. The matrix describes Open Science skills in two dimensions: areas of expertise and levels of expertise. The matrix comprises 11 areas of expertise and three levels of expertise, resulting in the description of 33 different competency profiles. The areas of expertise are derived from the Open Science Ecosystem and from an analysis of researchers’ needs and wishes regarding Open Science support services. 11 areas of expertise have been identified and described: Open Science policies, Data management planning, Rights & licenses, Literature & data search and data collection, Data storage, Data processing, Open Reproducible Research, Data archiving and long-term preservation, Data publishing, Scholarly communication/ publishing, Open Access publishing. General soft skills related to teaching, communication, and presentation have been excluded from the matrix, even though these are very important skills in supporting researchers. These soft skills are presented and discussed in the literature review [File 2.1]. The matrix describes the areas of expertise at three levels: Basic (KNOW), Intermediate (SHOW) and Expert (DO). These three levels of expertise describe both cognitive and behavioural competencies as well as expectations to which tasks an Open Science support professional can perform. The Competency Matrix can be useful for different stakeholders. For the library leadership, it is a useful strategic tool to optimize existing research support services and plan the development of new services at a given institution. For individual library staff, the matrix can serve as a basis for competency self-assessment and an aspirational roadmap of how to develop their professional competency profile. File 6.1 Competency matrix - PDF version Authors: Project group File 6.1 Competency matrix - XLSX version Authors: Project group