This paper examines whether the subjective beliefs on their competences of 409 trainees in machinery, sales, and logistics constitute a reliable and valid way to measure transferable competences. The analysis of results attributes satisfactory to good reliability values to the assessment procedure. Furthermore, it could be shown that young people with a higher dropout risk evaluated their methodological and social competences lower than those trainees with a lower dropout risk. Therefore it may be possible to prevent early dropout from vocational training through specific strengthening of these competences as well as through individual competence-based counselling during training.