The paper presents the major outcomes of a workshop held by INRAE in June 2022 on the practice of interdisciplinary PhDs in France, with the contribution of supervisors, PhDs, post-docs and directors of specific doctoral schools. Preliminary interviews, questionnaires, testimonies, input in epistemology and the discussions showed at the same time the interest of interdisciplinarity for both the supervisors and the doctoral candidates, and the difficulty of the task due, in particular, to the differences of the concepts and methods between disciplines. The seminar made it possible to clearly identify the favorable conditions for the good progress of interdisciplinary theses: carrying out a thesis in an interdisciplinary community; the profile of candidates already familiar with several disciplines or with a broad scientific background acquired through training or previous experiences; appropriate skills allowing the candidates to embrace new concepts and to assert themselves at the interface of disciplines; co-construction of the thesis project; support and accompaniment provided along the thesis, including training and tutoring. The practices regarding the management of interdisciplinary theses greatly vary from one doctoral school to the other. Several perspectives have been identified, related to the recruitment process, the training and accompaniment provided for supervisors and doctoral candidates, and the follow-up of the careers of young doctorate holders.