The English second language development of 19 children (mean age at outset = 5 years, 4 months) from various first language backgrounds was examined every 6 months for 2 years, using spontaneous language sampling, parental questionnaires, and a standardized receptive vocabulary test. Results showed that the children's mean mental age equivalency and standard scores on the Peabody Picture Vocabulary Test-Third Edition nearly met native-speaker expectations after an average of 34 months of exposure to English, a faster rate of development than has been reported in some other research. Children displayed the phenomenon of general all-purpose verbs through overextension of the semantically flexible verb "do", an indicator of having to stretch their lexical resources for the communicative context. Regarding sources of individual differences, older age of second language onset and higher levels of mother's education were associated with faster growth in children's English lexical development, and nonverbal intelligence showed some limited influence on vocabulary outcomes; however, English use in the home had no consistent effects on vocabulary development.