This research tested whether public school teachers display the positive feedback bias, wherein Whites give more praise and less criticism to minorities than to fellow Whites for equivalent work. It also tested whether teachers lacking in school-based social support (i.e., support from fellow teachers and school administrators) are more likely to display the positive bias and whether the positive feedback bias applies to Latinos as well as to Blacks. White middle school and high school teachers from 2 demographically distinct public school districts gave feedback on a poorly written essay supposedly authored by a Black, Latino, or White student. Teachers in the Black student condition showed the positive bias, but only if they lacked school-based social support. Teachers in the Latino student condition showed the positive bias regardless of school-based support. These results indicate that the positive feedback bias may contribute to the insufficient challenge that undermines minority students' academic achievement. (Contains 6 tables, 5 figures and 9 footnotes.)