Cities like New York and San Francisco have a different feel than cities like Newark and Columbus. But can these differences be captured quantitatively? We argue these places vary along the dimension of cosmopolitanism, that is, the extent to which they offer economic opportunities and emphasize diversity, creativity, and egalitarianism. We present a Cosmopolitan City Scale (CCS) designed to assess perceived cosmopolitanism. The CCS has high internal reliability and correlates with objective indicators of cosmopolitanism such as intergenerational mobility and number of patents generated (Study 1). Consistent with the notion that people with an independent orientation migrate to cosmopolitan places, independence was associated with preference for cosmopolitan cities as measured by our scale (Study 2). High openness to experience, high extraversion, liberalism, high socioeconomic status, and single marital status were also related to greater preference for cosmopolitan cities. We believe the CCS provides a new tool for understanding how cities differ and helps clarify factors that drive migration preferences. We also discuss implications of cosmopolitanism for cultural processes such as acculturation and intergroup relations.