This study investigates the cross-linguistic transfer of literacy skills in Spanish-English, Chinese-English bilingual, and English monolingual children (N = 283, 5-10 years). Research question 1 examines English literacy and asks how phonological and morpho-semantic skills contribute to word reading as a function of children's language background. Structural equation modeling revealed contrasting bilingual effects: compared to English monolinguals, Spanish-English bilinguals relied more on phonological awareness in word reading, whereas Chinese-English bilinguals relied more on lexical knowledge. Research question 2 examines relations between bilinguals' heritage language proficiency and English literacy. Results revealed direct and indirect effects of heritage language meta-linguistic skills on English word reading. The study yields implications for reading theories and instructional practices in optimizing literacy in linguistically diverse children.