In this book, we show the replacement of academic and vocational education, which is structured according to subject systems and oriented towards scientific knowledge, by vocational action knowledge. This work process knowledge is the basis for the acquisition of the design competence of vocational specialists, which is becoming increasingly important in the world of work. A modern knowledge concept based on vocational education is developed and documented. In the first part of the book the concept of vocational knowledge is developed, in the second part empirical results from COMET projects are documented, from which the vocational knowledge imparted in different occupations can be read. There has been a confusing discussion about vocational knowledge for decades. In 1991, the KMK agreed on a new concept for vocational education and training with the guiding idea of vocational design competence. It remained open on which vocational knowledge this new guiding idea shouldbe based. Up to now there has been no original vocational pedagogical justification for the vocational knowledge on which vocational design competence is based.