Despite their negative effects on the emotional, physical, and social wellbeing of students, weight stigma and anti-fat attitudes are rarely systematically addressed in schools or within school psychology. Weight-based oppression is regarded differently than other domains of prejudice. Therefore, implicit and explicit bias continue unimpeded, even when practitioners are attentive to other areas of social injustice. Mental health providers serving schools must acknowledge the prevalence of weight stigma and fatphobia to reduce their deleterious and oppressive effects. This conceptual paper outlines the underpinnings of weight stigma, overviews the necessity of addressing it and body image in educational settings, incorporates interdisciplinary perspectives, and proposes a justice-oriented shift in the conceptualization of weight status within school psychological service delivery.