limited proficiency in English, they are eligible for special services. Programs to serve the needs of these students vary considerably. In some cases, students receive some proportion of their instruction in their native language. In others, they receive instruction exclusively through the medium of English, but the English is simplified, and the instructional context is enriched to make the content more understandable. In still others, the special help comprises instruction in English as a second language (ESL), with a primary focus on the development of English-language skills, rather than on the academic content areas. Determining the relative efficacy of this range of approaches has been the principal focus of the educational policy debate.
But the debate has also been shaped significantly by political factors that go beyond educational techniques. The modern roots of this debate can be traced to the Civil Rights movement of the 1960s and federal involvement in education at this time. As Epstein (1977) pointed out early in the debate, the question of bilingual education, especially those programs that espouse the development and maintenance of the ethnic language, can be framed in terms of whether to pursue ''affirmative ethnicity" as an educational policy. The debate has also become an instantiation of related politically volatile issues, such as whether English should be constitutionally declared the official language of the United States (Crawford 1992), whether multiculturalism should be preserved (Graff, 1992; Hu-DeHart, 1995; Schlesinger, 1991), and whether national immigration policy needs to be changed (Brimelow, 1995). When ably used by politicians who wish to define themselves to voters or by the media when they wish to create controversy, the educational debate over how best to teach language-minority students is overwhelmed by these controversies.
The political issues outlined above cannot really be addressed by research; facts do not play a major role in these judgments. However, science and research are influenced by politicsfrom the research questions asked to the conduct of the studies and the way results are interpreted. Moreover, research in any highly controversial area invites suspicion and selective scrutiny from advocates of particular positions and must meet stringent demands to be credible and broadly accepted. The purpose of this report is to contribute to the construction of such a knowledge base in the education of students who are not fully English proficient by reviewing the state of knowledge and identifying a research agenda that will address the key knowledge gaps. We have endeavored to move beyond the narrow focus on language of instruction that has dominated the education and policy discussions.