Parameters have lain at the core of linguistic research in the generative tradition for decades. The theoretical questions they have raised are deep and broad: this reference text investigates how contemporary linguistics has best tried to answer them. This book looks at how parameters might be properly defined and what their locus might be :lexical information, functional heads, the computational system, the phonological branch of the grammar. What kind of data forms trigger acquisition of a parameter? Are parameters necessary or can we study languages without making reference to them? ...