From the “uncanny” in aesthetics to the psychotic delusional atmosphere, and from the occasional disruptions of reality in nevrosis to the neurological derealizations, feelings of strangeness cover a wide and heterogeneous range of experiences. These phenomena arouse a lot of clinical and epistemological issues, specially in the context of contemporary discussions of the notions of “attenuated psychosis” or “psychosis continuum”. A comparison between Janet’s and Freud’s descriptions of feelings of strangeness, and the analysis of delusional atmosphere provided by phenomenological psychiatry will lead to assess which clinical distinctions can be drawn within the experiences of strangeness, relying on different kinds of contact with one’s external and psychic reality.