Twenty-seven Mandarin–English bilingual children participated in picture identification and picture naming tasks at two time points, 16 months apart. The younger children (mean age = 4 years) showed greater gains over time than the older children (mean age = 6 years 10 months) in English lexical-semantic skills and neither group showed significant gains in Mandarin. At the individual level, a majority of the children showed increased accuracy for the English tasks, but only half of them did so for the Mandarin tasks. Analyses of error distribution indicated production of more advanced error types in the older children and in English, as well as different patterns of time-related changes in error types in the two languages. These findings illustrate how age and initial language proficiency are related to lexical growth among Mandarin-speaking bilingual children who are becoming English-dominant.
