Book excerpt: This book brings together papers by the foremost representatives of a range of theoretical and empirical approaches converging on a common goal: to account for language use, or how speakers actually speak and understand language. Crucial to a usage-based approach are frequency, statistical patterns, and, most generally, linguistic experience. Linguistic competence is not seen as cognitively-encapsulated and divorced from performance, but as a system continually shaped, from inception, by linguistic usage events. The authors represented here were among the first to leave behind rule-based linguistic representations in favour of constraint-based systems whose structural properties actually emerge from usage. Such emergentist systems evince far greater cognitive and neurological plausibility than algorithmic, generative models. Approaches represented here include Cognitive Grammar, the Lexical Network Model, Competition Model, Relational Network Model, and accessibility Theory. The empirical data come from phonological variation, syntactic change, psycholinguistic experiments, discourse, connectionist modelling of language acquisition, and linguistic corpora.