This study examined young Heritage Language (HL) learners' home literacy environment and its impact on HL word-knowledge development, focusing on a group of Chinese–English bilingual children learning to read in Chinese as a Heritage Language in the United States. A home literacy survey revealed that parents mostly used HL to talk to children, while learners preferred to use English or a mixture of English and HL to talk to their parents. Learners' HL reading practice at home showed a schoolwork orientation. There was a significant positive correlation between parents' language use and learners' HL vocabulary breadth; learners' schoolwork-related reading practice was also positively correlated with HL word knowledge. However, no significant relations were observed between independent and shared reading unrelated to schoolwork and learners' word knowledge. These findings are discussed in relation to the importance of school materials in HL literacy development and a possible threshold of frequency of schoolwork-unrelated reading that has to be passed for learners to be benefited.