The concept of basic Self-disorders (SD) captures the experiential aspects associated with vulnerability to schizophrenia spectrum disorders (SSD). SD emerge prior to, and constitute the underlying structure for, the emergence of major diagnostic symptoms, including positive psychotic ones. SD are also detectable in populations with familial risk for SSD. This paper proposes a two-stage phenomenological-developmental model, exploring the early deficit in multisensory integration and their impact on the ontogeny of the Minimal Self in the first years of life. It also examines subsequent emergence of schizotaxic vulnerability, which later manifests as typical anomalies of subjectivity, such as basic symptoms and self-disorders.