Introduction

Although there is no doubt that the rate of language development in children with Down syndrome is delayed in relation to their chronological age, results from a plethora of studies suggest that the sequence and structure of their early language development is largely similar to that observed in normally developing children (see Fowler, Chapter 9, this volume; Miller, in press; for recent reviews). An examination of different domains within language (phonology, syntax, semantics, pragmatics) and relationships of language with cognition and social development also reveals more similarities than differences (Beeghly & Cicchetti, 1985, 1986; Beeghly, Hanrahan, Weiss, & Cicchetti, 1985; Cunningham, Glenn, Wilkinson, & Sloper, 1985; Fowler, Chapter 9, this volume; Mervis, Chapter 8, this volume; Rondal, 1988). On the basis of these studies, most investigators conclude that there is not compelling evidence for a strong “difference” or “deficit” model of language development for these children, just as for mentally retarded children in general.

Nonetheless, important differences in the language development of children with Down syndrome also have been documented that are crucial to comprehend if we are to understand the process of development in these children. Perhaps the most striking difference is the dramatic delay in expressive language development of children with Down syndrome, relative to that observed in other retarded and nonretarded groups (see Chapter 9 by Fowler and Chapter 8 by Mervis, this volume, for reviews). Despite similarities in structure and sequence for most aspects of language, results of many studies document that individuals with Down syndrome show increasing linguistic deficits with advancing chronological age (Gibson, 1978; Miller, in press). Indeed, some individuals do not progress beyond early stages of syntactic development (see Fowler, Chapter 9, this volume; but see Rondal, 1988, for exceptions).