In this extraordinary book, Jackendoff proposes nothing less than a new way to understand the architecture of language and a new way to view the relation of language to the brain, to the mind, to behavior, and to the evolution of our species. It is, among many other things, an invitation for cooperation from one of the world's leading formal syntacticians to linguists of diverse orientations and to those from adjacent fields, including sociolinguistics and linguistic anthropology. If we don't want to be left behind, we had better pay close attention.