This study examined the psychometric properties of the Anti-fat Attitudes Scale (AFAS), a 5-item instrument developed by the authors to measure negative attitudes toward overweight individuals. A total of 4 studies were conducted among Canadian adolescents (n = 1,452) and university students (n = 424). Results suggested that the AFAS possessed a unidimensional factor structure and satisfactory reliability for both men and women. As predicted, men obtained higher scores than women on the AFAS, and antifat attitudes were positively associated with authoritarianism, homonegativity, and political conservatism. Participants who were overweight had lower scores on the AFAS than participants who were thin or average weight. Responses on the AFAS did not appear to be contaminated by social desirability bias.