The aim of this study is to examine which predictor variables are related to literacy attainment in Irish (Gaelic)-English bilinguals. The participants were in their second (n = 115) and third (n = 125) year of schooling in Ireland and were drawn from both native speaker and new speaker backgrounds. The constructs of phonemic awareness, verbal fluency (RAN) and verbal short-term memory were investigated as predictors of Irish word reading accuracy and spelling. The results indicate that the predictors of Irish and English literacy attainment differ, though phonemic awareness is the most effective predictor of literacy attainment in each language. Notably, the Irish predictor tasks were significant predictors of English literacy attainment, while the English predictor tasks were not significant predictors of Irish literacy attainment, supporting the unidirectional transfer of skills from Irish to English in this cohort. The implications of this study highlight the importance of developing bilingual screening and diagnostic assessments for literacy in the Irish-English context, something which is currently lacking.