This study investigated the relationship between first language (L1) literacy skills and second language (L2) reading comprehension and vocabulary development among students in Ghana. The study was grounded in Cummin’s (1970) Linguistic Interdependence Theory (LIT). The qualitative approach was adopted, and three instruments- focus group discussions, interviews and classroom observations- were used to obtain data from the sample of 300 secondary school students and 40 teachers. The researcher assessed participants' views in L1 literacy domains (phonological awareness, orthographic knowledge, and reading fluency) as well as their views on L2 (English) reading comprehension and vocabulary. The findings revealed a significant positive correlation between students' L1 literacy skills and their achievement in L2 reading comprehension and vocabulary. Those with more advanced abilities in their native language consistently demonstrated higher levels of reading comprehension and broader English vocabulary knowledge. This underscores the critical role of strong foundational literacy in the first language as a precursor to successful second language acquisition. The study also identified key instructional strategies that could help bridge the gap for ESL learners, such as explicit instruction in L1 literacy, structured opportunities for cross-linguistic transfer, and the incorporation of culturally relevant, mother-tongue materials into the curriculum. The implications of these findings for policymakers, curriculum designers, and teachers working to improve educational outcomes for linguistically diverse student populations are discussed.<p> </p><p><strong> Article visualizations:</strong></p><p><img src="/-counters-/soc/0799/a.php" alt="Hit counter" /></p>