Obese children experience disadvantages in school and discrimination from their teachers. Teachers’ implicit and explicit attitudes have been identified as contributing to these disadvantages. Drawing on dual process models, we investigated the nature of pre-service teachers’ implicit and explicit attitudes, their motivation to respond without prejudice, and how attitudes influence their judgments of an obese student. Results showed that implicit anti-obesity bias might stem from an implicit positivity toward thinness rather than from an implicit negativity toward obesity. Explicit attitudes were mixed: positive attitudes toward achievement, a dislike of obese persons, and neutral attitudes concerning blame and health responsibility emerged. Implicit and explicit attitudes affected judgments of language proficiency and intelligence: pre-service teachers with more positive attitudes judged the obese student more favorably. The results of multiple regression analyses suggest that attitudes might exert a greater influence when pre-service teachers must draw inferences to derive the judgment.