The rapidly changing labor market and the promotion of labor mobility lead to a demand for lifelong learning as well as the need for transparency and comparability of competencies. The application of skill classifications to describe competencies on educational certificates provides a way to document lifelong learning in a standardized way. In this paper, case studies regarding the application of the ESCO classification in three continuing education institutions are described. The results show that ESCO is a useful tool to document learning outcomes of continuing education courses in a comparable and transparent way but the mapping of competencies requires a lot of effort and differs in quality. The presented analysis identifies steps for further development of ESCO and for the change process when it comes to the standardized documentation of skills and competencies.