The current study explored the home and school factors that are important for Singaporean pre-schoolers' (N = 1440) early English development from K1 to P1. Language input quantity and quality factors at home (e.g., number of English books,) and at school (e.g., instructional support in class) were used to predict children's English vocabulary and word reading development using linear mixed-effects models. Children's internal factors (e.g., non-verbal reasoning) were controlled. The results revealed that children who had more English input and higher input quality at home demonstrated faster receptive vocabulary growth. Children's word reading skill was more influenced by the English input quality at home. Children who were frequently read to in English demonstrated faster development in word reading competence. Mother's educational level also mattered: higher maternal education was associated with faster growth in reading skill. The length of time children stayed at school and teachers' qualification also significantly and positively associated with children's English learning. These findings indicate the substantial contribution of the home literacy environment to Singaporean children's early English language development, compared to the quality of teacher-child interactions in preschool. The necessity of more parental involvement in early English language learning at home is discussed under the realm of usage-based theory.