This paper proposes a comprehensive framework for defining success in bilingual education. Defining success is a difficult and elusive task. Indicators of success are at the center of much controversy, and a review of the research of the last 30 years reveals varying trends in the underlying notion of success. Most studies focus on the ability of bilingual education programs to enhance students' performance in English academic areas, especially language and mathematics. By the late 1980s bilingual education researchers shifted their focus to identify characteristics of effective bilingual programs, as a part of the effective schools movement. This paper shows how research over the years has focused on certain components of the framework and how some recent trends are consistent with this broader definition. Definitions of success are discussed and followed by an overview of the current bilingual education debate--including the English-only movement, two-way immersion models, and traditional English-as-a-Second-Language (ESL) models. Studies of "Effective Bilingual Education" are discussed as well as studies that seek to put positive outcomes in context. It is concluded that there are two types of research--one type that that aims at judging the effectiveness of bilingual education centers by focusing on the language of instruction and models; the other type looks at specific instructional practices in detail. Good practices are likely to promote learning, but they do not guarantee student performance. Four tables and 53 references are included. (KFT)