The current study examined the relationship between interest, the home environment, and young Chinese children’s development of English as a second/foreign language in Hong Kong. Two hundred and seventy-four Hong Kong kindergartners were assessed on their interest in learning English and their English language skills (i.e., expressive and receptive vocabulary). Their parents completed questionnaires eliciting family socio-economic status, parental beliefs, and home learning environment. The results indicated that (1) interest was related to children’s English language abilities after controlling for children’s gender, non-verbal intelligence, and kindergarten type; (2) parents’ beliefs about their child’s English ability and self-efficacy were related to children’s interest in learning English; and (3) interest uniquely contributed to children’s English language ability in the home environment. The present findings provide evidence of the active role that children play in their second/foreign language development and highlight the significant influence of parental beliefs on children’s interest in learning English.