The sociology of health has paid much attention to the emergence of “lay experts”, and to the ways in which lay people reappropriate medical and scientific knowledge. However, little is known about what happens to lay knowledge when it is reappropriated by professionals. Such reappropriation is analysed through the case of mental health recovery. Four particular episodes are analysed: (1) the birth of recovery within users’ and survivors’ associations as a contestation of psychiatric expertise in the United States, (2) its reappropriation by North American psychiatric professionals, (3) its importation into French-speaking Switzerland and, finally, (4) its implantation into French-speaking Swiss health policies, notably through the training of peer practitioners. For each of these episodes, this paper explores the ways in which the relationship between the knowledge of users and professionals is reconfigured, as well as the tensions that arise around the distribution and recognition of expertise between the actors involved.