This paper explores the issues involved in the linguistic characterisation of disordered discourse and the ways in which a Systemic Functional Linguistic framework addresses these issues. For many years, language disorders were described in terms of formal grammars, with “breakdown” discussed in terms of one or more of the traditional levels of language, i.e., phonology, syntax, and semantics. While it was acknowledged that an individual could have difficulty at one or more of these levels, each was viewed quite separately, with semantics viewed largely from a referential perspective. More recent approaches using functional grammar have broadened this view of language and have provided a model of language that re-conceptualises the notion of meaning and embraces context as integral to its organisation. Such a model has introduced a different perspective on language into clinical fields, and has enabled researchers and clinicians to explore the skills of speakers with language disorders across a variety of situations and contextual variables, examining the linguistic resources still available to them. This paper introduces principles involved in a functional framework and provides an overview of how these principles have been applied to language disorders to date. In addition, the notion of “disorder” itself is discussed as it is situated in this alternative model.