During an investigation into the L2 proficiency and L3 acquisition skills of 10- to 12-year-olds in Irish primary schools, questions of metalinguistic awareness and cross-linguistic influence were raised. Do children who are more balanced bilinguals develop a higher sense of metalinguistic awareness than less balanced bilinguals? What evidence of cross-linguistic influence do those children display? Which language, or language teacher type, is most suitable in an Irish context for the development of these language learning skills? Following on from a primarily quantitative survey of all schools participating in the Modern Languages in Primary Schools Initiative in Ireland, and language testing of a smaller group of children, the evidence shows that more balanced bilinguals display a higher level of general proficiency and are more likely to independently display higher levels of metalinguistic awareness and evidence of cross-linguistic transfer. An examination of the features and characteristics of language and a summary of the main features of metalinguistic awareness and cross-linguistic influence provide a background for the results presented. The schools involved in the study include both early total immersion schools (Gaelscoileanna), where Irish is the language of instruction, and English-medium schools, where Irish is taught as L2. (Contains 2 tables.)