Social exclusion is related to many adverse mental health outcomes and may be particularly harmful for mental health in adolescence when peer relations become very important. This study examined associations between low peer status and psychotic experiences, psychosocial problems and short-term courses of these symptoms. A school-based sample of adolescents (N = 1171) was investigated in 2 consecutive years using the 16-item Prodromal Questionnaire and the self-report and teacher-report version of the Strengths and Difficulties Questionnaire (SDQ). Peer status was measured in the second year with positive and negative peer nominations of classmates. Low peer status was, after adjusting for gender, ethnic minority status and level of education, associated with more psychosocial difficulties with a persistent course and a higher level of psychotic experiences. Of all peer status groups, being neglected had the strongest associations with mental health problems. The results of this study show that social exclusion in adolescence is related to psychotic experiences and psychosocial problems, emphasizing the importance of belonging to a social group. Customized prevention programs at individual, family and school level should target causes and consequences of social exclusion.