As for all sorts of education programs, the first aim in doctoral education is to educate students with the skills they need in their professional life, as researchers in this case. Career opportunities for doctoral graduates can be found, obviously, in academia, but also outside it as employed by a non-academic organisation or as self-employed. For each of these career possibilities, collaboration is crucial. However, collaboration skills are not systematically integrated in doctoral education curricula, or at least not explicitly. Doctoral education thus calls for a reform to integrate the teaching of such skills; and this reform can happen only through the definition of collaboration skills and through the implementation of different kinds of collaboration opportunities.