Twice in the preschool/pre-k year, we assessed 37 Chinese 3- and 4-year-olds dual language learners' (DLLs) receptive vocabularies in English and Chinese, interviewed parents to gauge the home language environment, and videotaped classroom activities to analyze teachers' and DLLs' language use (word types) in English and Chinese. DLLs' receptive vocabulary grew in both languages but only English, not Chinese, language use increased. Teachers used more English than Chinese, but both languages showed declines over time. DLLs also engaged in more English than Chinese language and literacy activities at home. Teachers' language use was related to DLLs' language use in class within language, whereas language/literacy activities at home were related to DLLs' receptive vocabulary in the same language.