Children with dyslexia have lower self-esteem than children without dyslexia and this has been ascribed to their lower literacy abilities relative to their peers (Alexander-Passe, 2006; Glazzard, 2010; Humphrey, 2002). However, these studies have looked at monolingual, English-speaking children in the main. In Wales, the majority of schools are English-medium providing Welsh as a second-language subject but there are 517 Welsh-medium schools (Hughes, 2012)where children learn to read and write in Welsh and English. Research has found that literacy skills are more easily achieved in transparent orthographies (such as Welsh) than in opaque orthographies (such as English) (Seymour, Aro, & Erskine, 2003). This study examined the impact of bilingual education on literacy ability in children in Wales. It also investigated the impact of literacy instruction on the self-esteem of children in Welsh-medium and English-medium schools. 117 children in primary and secondary schools in North Wales participated. Standardised measures ofself-esteem, coping strategies andliteracy were used alongside a language use and background questionnaire to elicit details of self-perceptions of ability. Itwas found that children in Welsh-medium schools achieve expected standards of literacy in Welsh and in English by the first year of secondary school. This was mediated by the language used in the child’s home. Children with more balanced bilingual exposure across home and school performed best in measures of English literacy. Children in Welsh-medium schools had significantly lower self-esteem than those in English-medium schools at primary school age but had significantly higher self-esteem than children in English-medium schools at secondary school age. Self-esteem was found to be more closely related to literacy abilities in English for children in Welsh-medium schools. The results indicate there are significant benefits to bilingual education for children in Wales, including helping the development of literacy abilities. However, earlier introduction of English literacy instruction in Welsh-medium schools is advisable both to help improve English literacy abilities for all children and to protect self-esteem.