Radical Construction Grammar presents a profound critique of syntactic theory and argumentation, and offers a genuinely new approach to syntax based on the fact of grammatical diversity. Recent syntactic theories are essentially formal models for the representation of grammatical knowledge and posit complex syntactic structures in the analysis of sentences. The result has been a endless cycle of new and revised theories of syntactic representation. Radical Construction Grammar argues that this approach to syntax is incompatible with the grammatical variation found within and across languages. This book defends three fundamental theses: (i) constructions are the primitive units of syntactic representation, and grammatical categories are defined by constructions, not the other way around; (ii) the only syntactic structures are the part-whole relations between a construction and the syntactic elements that make it up; (iii) not only are grammatical categories construction-specific, but