Yes, it can. The co-direction of the doctoral thesis may be done in any of the three cases described below. Firstly, in cases where interdisciplinary work is needed and different areas of knowledge are required to develop the thesis work. Secondly, in cases of young doctors who want to learn to supervise theses. In this case, the thesis supervision should be done with and experienced doctor. Thirdly, in cases where the PhD thesis involves different universities or research centers. In this case, the PhD student will have a thesis supervisor in each one of the centers.