This chapter traces the evolution of language learner autonomy under the impact of transformative classroom practice. It begins by summarizing Holec's definition of the concept, and then describes an approach to teaching and learning that sought to operationalize that definition, but with two added features: use of the target language for all classroom communication; and a strong emphasis on collaborative learning. This gave the concept of language learner autonomy explanatory power: learners acquire L2 proficiency when their agency is channeled through the target language. The chapter then turns to inclusive education, describing an approach to the integration of immigrant pupils that engages their agency by encouraging them to use their home languages in the classroom. This enables them to develop a capacity for agentive behavior in English and Irish with the cognitive support their home language provides. The chapter concludes by briefly associating the two learning environments described with the concept of plurilingualism as it is defined in the Common European Framework of Reference for Languages.