Although generally acknowledged as complex and multidimensional, bilingual education, when successful, plays an important role in maintaining and developing bilingualism, resulting in numerous benefits to those who undertake it. This essay will discuss the necessary components and principles of what is required to make a successful bilingual program by defining what bilingualism is as well as critically analysing the benefits and drawbacks of such a program, with pertinent examples relevant to the overall present education system in Japan and what support is offered to foreign students and migrants to assist them in maintaining their first language. This paper will also address the very need for effective bilingual programs and what a bilingual individual is defined as. A number of major theories such as L1-L2 interdependency, critical period hypothesis, and additive and subtractive bilingualism will be explored to substantiate weak and strong forms of bilingual education. Other relevant social, psycholinguistic and cultural factors will also be discussed as will their implications and how they relate to ensuring bilingual programs succeed for minority and majority language students in their aims and objectives.