Most of the children attending bilingual immersion school programs in the French Community of Belgium learn to read in the immersion language before learning to read in their native language. This study aimed to explore the effect of learning to read in a second language having a transparent (Dutch) versus an opaque (English) orthographic code, on the later acquisition of French spelling. Because literacy acquisition depends on the orthographic depth of the code, the hypothesis is that learning to spell in a transparent language such as Dutch would promote the acquisition of the more opaque French spelling, by transferring the phonological recoding process. Contrariwise, the acquisition of French spelling would be less easy if learners were first immersed in very opaque spelling such as English. Participants were 182 third and fourth-graders immersed in Dutch or English, and monolingual French speakers (control group). Their French spelling skills were tested by words and non-words dictation. Results showed that the performance of Dutch immersed children was not significantly inferior to controls, which is not the case for English immersed children. This corroborates the fact that learning to spell in a more transparent orthographic code than French has a subsequent benefit on its acquisition.