Previous studies have found that phonological processing and vocabulary predict word reading. However, their predictive powers may vary according to reading experience and across scripts with different levels of transparency. In this study, the relationship between phonological processing, decoding, vocabulary and word reading was explored in two different alphabetic languages: Persian (a non-Latin script) and Swedish (a Latin script). Standardised tests in both languages were used. Participants comprised 26 Persian-Swedish bilingual (biscriptal) children in school grades 4-9. Rapid automatic naming (RAN), phonological and semantic fluency, non-word reading and vocabulary were all significantly associated with word reading in Persian, whereas phonemic awareness, RAN, phonological fluency and non-word reading were significantly associated with word reading in Swedish. The findings have been compared with previous research and the educational implications are discussed.