Previous studies have highlighted early differences in bilinguals' rate of language acquisition in comparison with monolinguals. However, these differences seem to disappear with increasing age and exposure to the language, and do so quicker in dominant community languages than in minority status languages. This study aimed to replicate these findings in relation to literacy development. Three groups of Welsh-English bilinguals (L1 Welsh, simultaneous bilinguals and L1 English) were given receptive vocabulary tasks and reading tasks in Welsh and in English. An additional group of monolingual English-speaking controls was given the English tasks. Results revealed differential performance among the bilinguals in relation to the English tasks, with the L1 English bilinguals and monolinguals performing closer to age norms than L1 Welsh and simultaneous bilinguals by the end of primary school education. No differences were found between the L1 English bilinguals and the monolinguals on either task. On the Welsh measures, performance mirrored those of previous studies, on both tasks, demonstrating higher levels of performance relative to increasing amounts of exposure to Welsh. The implications of these findings for bilingual education strategies, particularly in relation to the development of bilingual language competence in minority language situations, are discussed.