Improving the quality of dual vocational education and training (VET) is becoming increasingly important to meet the challenge of skills shortages. In this context, this article provides an overview of the development and current state of research on VET quality based on a systematic literature review. The findings of a conceptual overview of quality models since 1969 highlight how models of VET quality from both research and practice have adapted to changing understandings of VET teaching and learning processes over time, which are divided into four phases through a historical review of quality models. Furthermore, the article highlights the existence of a considerable number of measurement scales for empirically assessing the quality of dual VET. However, the conceptual analyses also reveal limitations in the current state of research, leading to identified needs for further research activities and initiatives. For instance, existing quality models and instruments often focus solely on the workplace learning environment, neglecting the incorporation of digitally-driven changes in work practices and cultures. Additionally, there is a shortage of qualitative studies that conceptualize training quality from the perspective of the stakeholders involved, as well as multi-perspective and process-oriented analyses within quantitative study designs. Finally, the article recommends the development of research-derived tools, in the form of mobile apps, for practical use. Not only can such tools be used to collect process-related information on quality facets, but it is also possible to link this with (AI-based) feedback mechanisms and use this as a basis for identifying starting points for the implementation of measures to increase the quality of the training process.