Experiencing discrimination based on body size has numerous health consequences and negatively affects motivation for positive health behaviors. Because weight bias is particularly prevalent among health professionals, interventions to reduce weight bias in this group are essential. The purpose of this mixed-methods, 15-week study was to develop and examine the effect of a college course focused on reducing weight bias in health promotion undergraduates. In this study (N = 64), quantitative change in implicit and explicit weight bias among students enrolled in a course to reduce weight bias was compared with a control group and two other groups of students in the health promotion degree program. Qualitative data were also analyzed through content analysis of pre- and postsemester writing assignments among students in the course focused on weight bias. Statistical analyses revealed a significant reduction in explicit weight bias among students in the course focused on weight bias with no significant changes in explicit weight bias for any other group. There were no significant changes in implicit weight bias for any group. Content analysis of qualitative data was consistent with the quantitative reductions in extrinsic weight bias. Students shared substantially more nuanced understandings of obesity postsemester. Furthermore, the persistence of internal contradictions in students’ analyses illustrates the particular challenge in reducing implicit bias. These results demonstrate that, although intrinsic weight bias may be more difficult to change, a college course focused on reducing weight bias can facilitate significant reductions in extrinsic weight bias among health promotion undergraduates.