Using thousands of concepts in public data sets and computational resources, the study provides evidence for claiming that abstract and concrete concepts are organized and represented differently in the mind. First, abstract and concrete concepts are shown to have differing patterns of association with other concepts. Second, the authors move on to test recent hypotheses that abstract concepts are organized according to association and concrete concepts are organized according to (semantic) similarity. Third, the authors provide evidence for suggesting that concrete representations are more strongly feature-based than abstract concepts. Indeed, degree of feature-based structure may fundamentally determine concreteness. The implications for cognitive and computational models of meaning are discussed.