‘I don’t feel love for my partner anymore: can I trust this feeling, or do I feel this way because of my depression?’ ‘Does my medication allow me to be myself, or am I just drugging myself to function better?’ Questions like these are omnipresent in psychiatry. For psychiatric disorders precisely pertain to how a person feels, thinks, perceives, and/or acts. This opens up the question of which thoughts and feelings are genuine expressions of me, and which are expressions of my disorder. As treatment is directed at those very same experiences, a parallel question arises here: is my medication only suppressing my symptoms, or is it (subtly) altering me? And: how can I tell? While such questions are taken from psychiatric practice, they bear directly on philosophical issues and theories. For what does it mean to ‘be oneself’? Is there even such a thing as being ‘an authentic self’? This project aims to develop an innovative philosophical, empirically sound theory of authenticity in psychiatry by combining philosophical analysis with qualitative research on the experiences of people who suffer from Major Depressive Disorder (MDD). Specifically, the project will (1) investigate MDD patients’ experiences of ‘ownness’ and ‘alienness’ with regard to their disorder and their treatment, (2) analyse philosophical theories of authenticity for dynamic, relational subjects and explore what a relational take on authenticity implies for the possibility of socially supported or ‘scaffolded’ authenticity, and (3) assess the implications of the concepts developed in (2) in the psychiatric context. Various clinical studies have established that questions of authenticity are a major concern to psychiatric patients. What is lacking, however, is a comprehensive account of the problem of authenticity in psychiatry that addresses these concerns. By providing such an account, this project aims to contribute to better mental healthcare.