According to the “script dependent” hypothesis, accurate word recognition skills develop more slowly in languages with an irregular orthography, such as English, than in regular orthographies, such as Persian. According to the “central processing” hypothesis, basic reading skills in all languages are influenced primarily by underlying cognitive factors. These hypotheses were examined by studying the linguistic, cognitive, and basic reading skills of 70 children in Grades 1–5 learning to read concurrently in English (L1) and Persian (L2). Our findings supported both hypotheses. A consideration of these frameworks as complementary contributes to a crosslinguistic theory of reading skills development in bilingual children.