Developing literacy in two languages can be challenging for young bilingual children. This longitudinal study investigates the effects of bilingualism in the spelling strategies of English-Portuguese speaking children. A total of 88 six- to-seven-year-old bilinguals and monolinguals were followed during one academic year and data gathered on a range of verbal and written language skills and non-verbal measures while controlling for SES. For both bilinguals and monolinguals letter knowledge, phonological awareness and word concept were significant predictors of spelling. However, non-verbal reasoning played an increasing role in explaining spelling variance for bilinguals, suggesting that learning to spell in two alphabetic languages places more demands on non-verbal processing skills. Spelling error analyses further revealed that bilinguals when compared to monolinguals showed more reliance on phonological strategies, less compliance with the L1 orthographic system and at times transference from L2. The results suggest important implications for our understanding of spelling acquisition and the development of effective intervention practices for bilingual children.