This chapter describes a total of 32 studies, 11 studies focusing on pre-service teachers, 15, on in-service teachers, and six related to learners. Most are qualitative studies, and the number of participants ranges from 1 to more than 600. After the descriptions, studies are compared and contrasted in terms of theoretical implications, and in another section, the strands are drawn together in terms of the recommendations across the studies. Generally, there is a strong emphasis on the need for designing bilingual education to suit the particular context. The studies represent a wide range of geographical contexts, representing bilingual, colonial and immigrant contexts, and also report on monolingual contexts, particularly Turkey, where much pioneering work has been conducted by the authors.