The COVID-19 crisis has reiterated the importance of adult learning and career guidance services as many adults have lost their jobs and now require upskilling and reskilling opportunities in order to keep pace with the rapidly evolving world of work. Yet, in order to achieve its positive gains, adult training needs to be of high quality and ensure successful learning experiences for all participants. This report therefore aims at supporting public authorities to enhance quality in the field of non-formal adult learning. It provides an overview of quality assurance systems across Europe, highlighting their implementation features, governance structures and success factors. Based on this analysis, the report develops a Quality Assurance in Adult Learning Decision Tree to support the decision-making process of governments that are planning reforms of their quality assurance systems.