1 To appear in Graeme Trousdale and Thomas Hoffmann (eds.), The Oxford Handbook of Construction Grammar. Oxford: Oxford University Press. Chapter 16. Construction grammar and first language acquisition Holger Diessel 1. Introduction There are two major theoretical approaches to the study of grammatical development in first language acquisition. The nativist approach, which rests on central assumptions of generative grammar (cf. Chomsky 1972), and the usage-based approach, which is closely associated with construction grammar (cf. Tomasello 2003). The two grammatical theories make radically different assumptions about the nature of grammatical elements and the overall organization of the grammatical system. Generative grammar is a formal syntactic theory that has crucially influenced research on first language acquisition for several decades (see O’Grady 1997 for an overview). In this approach, the core of grammar consists of invariable concepts and constraints that are predetermined by an innate ‘language faculty’ (see Pinker and Jackendoff 2005 for a recent discussion). There are two central assumptions that underlie the analysis of syntactic structure in this approach. First, generative grammar is based on the assumption that the language faculty consists of modules. According to Chomsky (1965), (mental) grammar can be divided into three basic components: syntax, semantics, and phonology. Each component (or module) has its own categories and rules that are in principle independent of each other. On this account, syntactic representations are autonomous in the sense that they can be analyzed without reference to meaning. Second, generative grammar is based on the assumption that syntactic representations are derived from a universal set of syntactic categories. Although there is no general consensus among generative grammarians as to which categories are universal (and innate), researchers agree that grammatical categories have to be defined prior to and independently of particular syntactic configurations. On this account, syntactic representations are formed from syntactic primitives that provide the building blocks for the analysis of syntactic structure in all languages. Both assumptions, i.e. the assumption that syntax is autonomous and that syntactic structures are derived from primitive categories, are based on the innateness hypothesis of generative grammar. According to this hypothesis, children are born with a universal set of formal syntactic categories, to which generative grammarians refer as ‘universal grammar (UG)’ or the ‘language faculty’ (cf. Pinker and Jackendoff 2005). What children have to learn in this approach is how words and structures of the ambient language are related to elements of UG (cf. Pinker 1984). According to Chomsky (1999), grammatical development is a particular cognitive phenomenon that must be distinguished from learning—a term that