On one widespread view, language maps word-forms to concepts. On this view, concepts exist independently from and prior to language. Alternatively, many of our concepts — including some that seem very basic—may derive from our experience with, and use of, language. On this alternative, language takes on a more transformative role in augmenting human cognition. I will argue in favor of this second view and present several studies showing how words help structure and align our concepts by serving as categorical overlays on thought and perception.