Nowadays, it is broadly acknowledged that ethos is an important element of professionalism. Ethos was defined to be a person's active commitment to the professional responsibility. For its development, an important condition is a sense of responsibility. This paper studies at the example of vocational trainers which characteristics contribute to the establishment of a sense of pedagogical responsibility. The study was outlined as a mixed-method design consisting of two phases, a qualitative study in order to develop the responsibility scales as well as a quantitative part. In latter, totally 570 vocational trainers of two different occupations were questioned. Findings showed that different experiences with vocational education influenced the trainers' sense of responsibility. The most important predictor was found to be a trainer's feeling of being significant for the apprentices' success. The results are of practical value, not only for training institutions but for professional associations, company managers, and society in general.