Book excerpt: Research literature concerning the effects of incorporating the heritage languages of minority students into the regular school curriculum either as subjects or as mediums of instruction is reviewed. Program evaluations from Canada, the United States, and Europe consistently show that the use of a minority language as a medium of instruction for all or part of the school day entails no long-term loss in the development of academic skills in the majority language. There is also evidence that bilingual programs can both encourage minority parent involvement in their children's schooling and facilitate the development of minority students' academic skills. However, this pattern does not invariably emerge in the evaluation data, and further research is required to understand fully the complex interactions that appear to exist between language of instruction and a range of individual, educational, and social factors. Virtually no research data are available on the academic effects of teaching heritage languages as subjects, as opposed to using the languages as a medium of instruction. Also, because most program evaluations focus primarily on academic outcomes, little or no data are available on the impact of bilingual or heritage language programs on the educational system as a whole. Three major policy implications of the research are addressed. (Author/SW)