In this article, we review some important controversies about concepts in the philosophy of psychology, focusing particularly on the theories of concepts developed in philosophy, on the debate about the homogeneity of concepts, on neo-empiricism, and on concept learning. WIREs Cogn Sci 2012, 3:265-279. doi: 10.1002/wcs.1166 For further resources related to this article, please visit the WIREs website.