We explore what people mean by “diversity” when they use the term to describe real communities. “Diversity” can refer to multiple differences—ethnoracial, economic, and so on. It may also refer to multiple dimensions of the same difference, that is, heterogeneity or group representation. Analyzing a survey of Chicago-area residents, we ask: (1) When people describe a community as diverse, on which kinds of differences are they drawing? (2) Within each relevant difference, are evaluations of diversity predicted by heterogeneity, the share of specific groups, or both? Findings suggest that respondents associate diversity primarily with a community’s ethnoracial attributes and secondarily with its economic attributes. Within ethnoracial attributes, both heterogeneity and the share of disadvantaged ethnoracial groups, especially Blacks, predict assessed diversity. Within economic attributes, income inequality predicts assessed diversity, albeit negatively; the representation of poor people does not. Qualitative responses reveal varied understandings of diversity while confirming the dominance of ethnoracial attributes.