An ever-increasing need for a bilingual education in globalized societies have set new challenges for all stakeholders from ideological (monoglossic vs heteroglossic) as well as methodological perspectives. Teachers' persistent interest in different forms of bilingual education has attracted us to explore the potential of Content and Language Integrated Learning (CLIL) as a means of attaining a bilingual education in the second decade of the 21st century, especially the professional development of teachers who work in the given context. In this study, narrative analysis is employed to investigate how teachers' explicit meaningful experiences lead a teacher to become a CLIL teacher in the Estonian educational settings, and disclose the factors shaping this process. The results reveal a variation in the teachers' meaningful experiences driven mostly by their context -- the type of bilingual program, the status of the foreign language, school support for collaborative practices - as well as a variation in the belief of what constitutes CLIL - views on languages and personal pedagogical beliefs.