Results of a National Research Council review of two major bilingual education studies are presented. The two studies were a national longitudinal study of the effectiveness of instruction of limited-English-proficient students and a study comparing three bilingual education program types (immersion, early exit, and late exit). The report contains six sections. The first gives an overview of this review's research and policy contexts, describes the two studies, and outlines the report's contents. The second section offers information about the research methodology used for bilingual education, including collection of statistical data, definition of outcomes and treatments, units of analysis, and appropriate kinds of inferences. Sections 3 and 4 describe the two studies, longitudinal and comparative, respectively, and detail the findings of their separate reviews. The fifth section looks at lessons learned during the process, concerning specifying objectives for bilingual education, developing interventions based on theory, and designing and implementing experiments. Section 6 outlines conclusions and recommendations drawn from the review. Appended materials include: a brief history of bilingual education in the United States; a discussion of trajectory analysis of matched percentiles, a graphical methodology; a list of acronyms; biographical sketches of review panel members and staff; and a bibliography. (MSE)