ABSTRACT
This chapter considers the children for whose non-normal language acquisition there is no identifiable physical or psychological basis. Lying as it does at an intersect of language acquisition studies and developmental psychology, as well as providing an interest for behavioural genetics, specific language impairment (SLI)attracts a diversity of methodological approaches, descriptive frameworks, and explanatory accounts. This does not always make it easy to see what the fundamental problem is, or how to deal with it educationally. There are problems with subject description and characterisation, both within and across languages, that make generalisations suspect. The chapter concentrates on data and explanations arising from the finding that in the cross-sectional studies, it has become apparent that English-speaking SLI individuals, at least, have particular problems with grammatical morphology. Nevertheless after a couple of decades of empirical work, mostly on English, recent cross-linguistic research, and more sophisticated approaches to possible causes of the problem, suggest that the brink of interesting developments in the field.
