There are a number of standards aiming to facilitate the exchange of competence data in the educational and job market areas. Despite their relevance, we have observed that they could benefit from an in-depth analysis of the notion of competence, given its central role in the intended application areas. This includes addressing facets of competence not only when attributed to particular individuals, but also when required by occupations in general. A comprehensive account for competences should ideally account for competence-related elements such as knowledge, attitudes, skills. It should also countenance their performance—related to tasks, their context, and outcomes—as well as their evolution over time (in order to account for the notion of ‘proficiency’). While some of these aspects are addressed in the existing standards, they are addressed in a partial manner, and a comprehensive conceptualization that can serve as a reference for articulating the various perspectives is still lacking. This is the focus of Core-O as a well-founded competence reference ontology.