Social avoidance in young patients is a clinically worrisome phenomenon that characterizes impending schizophrenia, but that also constitutes a core phenomenon in avoidant personality disorder (AvPD), schizoid personality disorder (ScPD), and in autism spectrum disorder (ASD). Especially in the absence of any other clinically relevant phenomena, understanding the origins of social avoidance may be one the most challenging tasks in assessing whether adolescents and young adults are at risk for developing schizophrenia. Descriptive and psychometric assessments only allow to comment on the absence or the presence of this phenomenon, but do not capture the origins and the meaning of social avoidance. Based on a narrative review, we highlight the importance of a phenomenological approach to unveil the Gestalt of social avoidance in these mental disorders, including and appraisal of the underlying mental structures and attachment styles. The phenomenological approach allows to distinguish the Gestalt of social avoidance between AvPD, ScPD, ASD, and beginning schizophrenia, to ensure correct diagnostic labelling and optimal treatment, and to avoid unwarranted stigmatization.