This study examined metalinguistic awareness in children who were becoming bilingual in an immersion education program. The purpose was to determine at what point in emerging bilingualism the previously reported metalinguistic advantages appear and what types of metalinguistic tasks reveal these developmental differences. Participants were 124 children in second and fifth grades who were enrolled in either a French immersion or a regular English program. All children were from monolingual English-speaking homes and attended local public schools in middle socioeconomic neighborhoods. Measures included morphological awareness, syntactic awareness, and verbal fluency, with all testing in English. These tasks differed in their need for executive control, a cognitive ability that is enhanced in bilingual children. Overall, the metalinguistic advantages reported in earlier research emerged gradually, with advantages for tasks requiring more executive control (grammaticality judgment) appearing later and some tasks improving but not exceeding performance of monolinguals (verbal fluency) even by fifth grade. These findings demonstrate the gradual emergence of changes in metalinguistic concepts associated with bilingualism over a period of about 5 years. Performance on English-language proficiency tasks was maintained by French immersion children throughout in spite of schooling being conducted in French.