Criteria lists of academic skills are widely used to assess the work readiness of people who are looking to enter or re-enter the apprenticeship market. These instruments represent a particular hurdle in the path to vocational training for low-skilled would-be trainees. We investigate the validity of one such list used in Germany. As different workplaces have diverse requirements, we question whether the same criteria hold for various professions. The study surveyed 538 trainees enrolled in vocational training programmes in eight different professions. Participants were asked about the requirements of their professions with respect to the minimum standards (as specified in the German Catalogue of Criteria for Apprenticeship Readiness) for work readiness. The results showed that the trainees consider the requirements during training to be lower than the minimum standards specified in the German Catalogue of Criteria for Apprenticeship Readiness and that substantial heterogeneity in requirements exists both between and within professions. We argue that criteria lists, which are also used in other countries in similar ways, should be treated with caution, as they might not be able to predict would-be trainees' readiness to successfully complete an apprenticeship programme due to enormous variability in job requirements.