The study examined the relationship between children's explicit knowledge and awareness of diglossia (EKAD) and learning Arabic in school. Additionally, this study addresses the interrelationships between EKAD and oral comprehension, lexical, phonological, and morphosyntactic awareness upon the transition to reading to learn. Thirty typicaly developing Arabic speaking fifth and sixth graders were randomly recruited (n = 18 males). The Arabic diglossic Knowledge and Awareness test (ADAT) was administered to examine the interrelationships between diglossic awareness and children's Arabic reading and mathematical abilities. Results showed that children depicted varying diglossic knowledge and awareness with no significant effect of gender, age, or academic grade. Children's EKAD scores significantly predicted their scores on Arabic reading and writing test but not their math scores. The contribution of EKAD was beyond that of phonological awareness. Significant corelation was also found between EKAD and phonological awareness. These results indicate that children's academic success at advanced stages of Arabic learning is related to explicit knowledge and awareness of diglossia. In turn, this provides support for the role of diglossic/bidialectal awareness as an independent emergent skill during literacy acquisition in diglossic communities and the need to incorporate it into the educational and clinical assessment of emergent literacy among diglossic communities.