Peter Culicover offers a constructional approach to language variation and change based on grammatical complexity. The volume is divided into three parts: the first establishes the theoretical foundations; the second explores variation in argument structure, grammatical functions, and A-bar constructions, drawing on data from a variety of languages including English and Plains Cree; and the third examines constructional change, focusing primarily on Germanic. The study ends with observations and speculations on parameter theory, analogy, the origins of typological patterns, and Greenbergian 'universals'.