The extant literature includes conflicting assertions regarding the influence of
bilingualism on the rate of language development. The present study compared the
language development of equivalently high-SES samples of bilingually and
monolingually developing children from 1 ; 10 to 2 ; 6. The monolingually
developing children were significantly more advanced than the bilingually
developing children on measures of both vocabulary and grammar in single
language comparisons, but they were comparable on a measure of total vocabulary.
Within the bilingually developing sample, all measures of vocabulary and grammar
were related to the relative amount of input in that language. Implications for
theories of language acquisition and for understanding bilingual development are
discussed.