Background Context: In most immigrant-receiving societies, an important question, both for researchers and policy makers, has been the weighing of the relative efficiency of different formulas in the learning of the host language by immigrant students, especially the potential impact of specific services on social integration and the role of heritage languages. Purpose/Objectives/Research/Question/Focus of Study: This article tries to go beyond the most conspicuous elements of these controversies to look at the variety of practices that different societies have adopted. Given the questions just raised, a specific focus is given to the degree to which such endeavors follow an immersion or specific services formula on the one hand, and to the role that they grant to heritage languages on the other. Five major immigrant-receiving societies have been chosen, and their choices regarding either issue are contrasted: Britain, two Canadian provinces (Quebec and Ontario), the United States, and Belgium (Flemish Brussels). Research Design: To ascertain the extent to which transferable conclusions about best models and practices can be drawn from international comparison, evaluation research on the strengths and weaknesses of each of these formulas is reviewed, with a focus on their short and middle-term linguistic outcomes given the paucity of data on their long-term educational and social outcomes. In conclusion, we identify the minimum threshold of consensus regarding the policy and program conditions that foster a proper mastery of the host language by immigrant students without jeopardizing other dimensions of their school or social integration. Conclusion/Recommendations: Three recommendations for policy makers can be drawn. First, flexibility and diversity of formula, both regarding the specific-services-versus-quick-integration dilemma and the place of heritage languages, seems a much better option than the one-size-fits-all model given the great variety found within the immigrant student population. Second, regardless of the model adopted, a fundamental winning condition lies in the recognition that the linguistic integration of newcomers is a collective responsibility and thus necessitates the establishment of close links between specific services, whenever they exist, and regular classrooms. Finally, research points to the necessity of focusing attention on schools and classrooms, especially pedagogical practices and teaching strategies, instead of being obsessed with models and formula.