This paper compared the vocabulary size of a group of 250 bilinguals aged 24–36 months acquiring six different language pairs using an analogous tool, and attempted to identify factors that influence vocabulary sizes and ultimately place children at risk for language delay. Each research group used adaptations of the MacArthur-Bates Communicative Development Inventories: Words and Sentences and a specially designed developmental and language background questionnaire to gather information on risk factors for language impairment, demographic and language exposure variables. The results showed a wide range in vocabulary development which could be somewhat attributed to mothers’ education status, parental concerns about language development and amount of exposure to the second language. We looked at those children performing below the 10th and above the 90th percentile to determine what factors were related to their vocabulary size. Features of the entire group of lower performing children were fewer than 50 words and the absence of two-word combinations by 24 months, lower levels of parental education and parental concerns about language development. The implications for identifying bilingual children at risk for language impairment as well as the language enrichment that might be needed for young bilinguals are outlined.