Bilingual education and second language immersion programs have operated on the premise that the bilingual student’s two languages should be kept rigidly separate. This paper argues that although it is appropriate to maintain largely separate spaces for each language, it is also important to teach for transfer across languages. In other words, it is useful to explore bilingual instructional strategies for teaching emergent bilingual students rather than assuming that monolingual instructional strategies are inherently superior. The central rationale for integration across languages is that learning efficiencies can be achieved when teachers explicitly draw their pupils’ attention to similarities and differences between their languages and reinforce effective learning strategies in a coordinated way across languages. The paper explores the interplay between bilingual and monolingual instructional strategies within French immersion programs, and bilingual education more generally, and suggests concrete strategies for optimizing students’ bilingual and biliteracy development.