In this chapter we propose to retrace the trajectory that led our teams to develop clinical research projects on the contributions of family therapy in the treatment of anorexia nervosa among adolescents and young adults, and the advantages of this approach. In the first part we will successively describe the context that led to the first trial deployed in France (The THERAFAM randomised controlled trial), the way in which we proceeded and the results of this initial work. In the second part we will explain how, in an international context advocating the development of multi-family therapy, and in the light of the results of our first study, we designed a second research project which is currently underway (The THERAFAMBEST randomised controlled trial). We will successively describe the development of the user manuals for the two therapies, systemic family therapy and multi-family therapy, and how the programme is still underway despite the difficulties we have had to face.