The core aim of this project is to unravel the experiential mechanisms through which delusions in schizophrenia spectrum disorders are formed and maintained. To this end, the Deluded By Experience project adopts a phenomenological approach that focuses on the role of disturbances in the experience of self and reality in delusion formation. Three core experiential disturbances will be considered: hyperreflexivity, diminished sense of self-presence, and disturbed grip/hold on reality. We will also assess the effect of context, emotion regulation strategies and person-level differences on the dynamics of self-reality disturbances and delusions. The main hypothesis is that disturbances of self and reality can predict the formation and maintenance of delusional episodes. To validate this hypothesis, a mixed-method approach combining intensive longitudinal assessment methods (ESM) and qualitative inquiry will be used. This will allow studying delusion as an experientially motivated, dynamic, contextually bound, and person-specific phenomenon. Results of this project could enable a new understanding of delusion formation with potentially crucial implications for their clinical management and treatment.