The present research aimed to determine how people define and perceive diversity in historically majority-group dominated contexts. I hypothesized that diversity conveys both the numeric representation of racial minorities and the social acceptance of racial minorities, and that these two themes would serve as the basis for individuals' perceptions of groups' diversity. I also investigated whether the concept of fairness was relevant to mental representations and perceptions of diversity. In Study 1, I found that businesses professing commitment to diversity defined it primarily in terms of social acceptance. Fairness and numeric representation of minorities were secondary themes in businesses' diversity statements. In Study 2, I found that individuals defined diversity primarily in terms of numeric representation of racial minorities and secondarily in terms of social acceptance of minorities, but not in terms of fairness. In Study 3, I investigated whether cues to numeric representation and social acceptance levels of a group were used in perceptions of diversity. I found that college undergraduates' perceptions of diversity were driven by both cues to representation and to social acceptance. In addition, White students were more likely to base perceptions of diversity on a cue to representation whereas Latino students were more likely to base their perceptions of diversity in a cue to social acceptance. Finally, in Study 4, I demonstrated that numeric representation and social acceptance causally led to perceived diversity. However, social acceptance only influenced perceptions of diversity when numeric representation was high. Across the four studies, I showed that social acceptance and numeric representation are both important components of diversity and serve as the basis for perceiving diversity in groups.