People form evaluative judgments of others after mere glimpses of them. Although the consequences of these judgments have been well documented, the proximal factors that give rise to them remain less clear. Here, I integrate research from the social, cognitive, and vision sciences to argue that visual exposure guides impression formation. Specifically, I propose that perceivers visually adapt to others’ appearances, forming preferences for phenotypes they encounter frequently and prejudices against phenotypes they encounter infrequently. Study Set 1 tested this theory with regard to gendered facial features. In Study 1, visual adaptation to feminine faces caused feminine features to appear increasingly normative whereas visual adaptation to masculine faces caused masculine features to appear increasingly normative. Studies 2 and 3 extended these findings to evaluative judgments: Visual adaptation to feminine faces exacerbated a baseline bias against targets with masculine relative to feminine features, whereas visual adaptation to masculine faces mitigated it. Studies 4 and 5 revealed that popular media can act a naturalistic form of exposure that molds preferences for gendered facial features, insofar as perceivers who reported a high degree of exposure to media depicting hyper-feminine women (Study 4) and perceivers who were experimentally exposed to media images of hyper-feminine women (Study 5) espoused especially strong biases against masculine female faces relative to feminine female faces. Study Set 2 extended my initial findings to evaluative judgments related to body weight. In Study 6, exposure to thin bodies lowered the threshold for labeling others as fat whereas exposure to fat bodies heightened the threshold for labeling others as fat. Study 7 linked these threshold shifts to social evaluations, indicating that exposure to thin bodies exacerbated biases against fat targets relative to thin targets whereas exposure to fat bodies mitigated them. Using eye-tracking technology, Studies 8 and 9 revealed that perceivers unintentionally gazed at thin bodies more than fat bodies when presented with both simultaneously, which heightened evaluative preferences for thin bodies relative to fat bodies. Study 10 showed that this tendency to gaze at thin bodies can be overcome with a simple gaze manipulation in order to reduce prejudice against fat targets. Collectively, these findings offer new insights into the perceptual underpinnings of impression formation while emphasizing visual exposure as a cost-effective method for reducing prejudice against social groups that are stigmatized on the basis of their physical appearance.