The Grammar of Q puts forth a novel syntactic and semantic analysis of wh-questions, one that is based upon in-depth study of the Tlingit language, an endangered and under-documented language of North America. A major consequence of this new approach is that the phenomenon classically dubbed "pied-piping" does not actually exist.

Cable begins by arguing that wh-fronting in Tlingit does not involve a syntactic relationship between interrogative C and the wh-word. Rather, it involves a probe/Agree relation between C and an overt "Q-particle" (or "Q") c-commanding the wh-word. Fronting of the wh-word in Tlingit is a mere by-product of fronting the QP projected by this Q. From this core observation, he develops a syntax and semantics for Tlingit wh-questions.

Given the strong similarity between the wh-constructions of Tlingit and those of more widely studied languages, Cable applies his analysis to a range of other languages and finds that such a "Q-based" theory holds a number of interesting consequences in syntax and semantics.