In bilingualism there are rigorous arguments among researches on the inclusion of second language in early phases of L1 education. While some researchers support such inclusion, others advise that doing so might adversely affect the first language. In the context where this study was conducted (Saudi Arabia), despite the heated debate on introducing English to the Saudi primary schools, only few studies attempted to investigate the effect of teaching English from the first grade on the Arabic literacy skills. This research is a response to the lack of empirical evidence about the impact of learning a foreign language at a young age on L1 by investigating the effect of early bilingual education on the reading and writing (literacy) of Arabic (L1). The study was conducted on students from two Saudi elementary schools: a public school and a private school. The sample comprised 46 Arabic-speaking female students from grades two. The children were subdivided into 2 groups: 30 monolingual students and 16 bilingual students. The children took diagnostic tests to measure their linguistic development in their mother tongue. Over all, the results showed no negative impact on the reading and writing skills of Arabic if English is taught from the beginning of formal schooling.