Individuals with psychosis are often subject to external stigma and discrimination and commonly also experience internalized stigma. Attempts to improve attitudes have tended to medicalize the experiences associated with psychosis; however, research increasingly indicates an association between biogenetic attitudes and stigma. This study aims to evaluate this approach by investigating the impact of two different etiological explanations on both internalized and external stigma in people experiencing psychosis. A total of 60 participants who have a diagnosis of schizophrenia or meet criteria for early intervention services for psychosis were randomly allocated to one of two conditions (psychosocial vs. biogenetic). Attitudes were assessed before and after the intervention. Both interventions resulted in a decrease in internalized stigma. Only the psychosocial intervention decreased external stigma. Although further research is necessary, providing education to individuals could be an effective way to reduce internal stigma. Antistigma campaigns should avoid a singular focus on biogenetic explanations of psychosis, and a psychosocial viewpoint may be a suitable alternative. (PsycINFO Database Record (c) 2019 APA, all rights reserved)