A reconsideration of the relation between age and mean utterance length.

Although a linear relationship between age and utterance length during the preschool years has been reported, that result was only partially replicated from age 2 to 5 years in two new research samples, one cross-sectional and the other longitudinal in design. Instead, a deceleration in age curves, particularly beyond about 36 months, was observed in each sample. Some explanations and implications of the findings are discussed from normative and developmental viewpoints.