The classroom demographics in French immersion (FI) programs across Canada are changing: There are a growing number of multilingual students who are learning English as a second language (L2) and French as a third language (L3). However, little is known about the development of French language proficiency and reading skills of multilingual students in the FI programs. The association between sociolinguistic factors as well as metalinguistic awareness, language proficiency, and literacy skills in the L2 and language proficiency and literacy skills in the L3 was investigated in this study. The sample included 55 students with an average age of 11 years and six months, in early FI programs who were tested at the end of Grade 6. Multiple regression analyses revealed that oral language proficiency and reading comprehension in English predicted oral language proficiency and reading comprehension skills in French, controlling for amount of reading in French and morphological awareness in English. This study demonstrated that although the majority of instruction in FI programs is in French, multilingual students continue to develop age-appropriate oral language proficiency and reading skills in English and French.