This article argues that the Council of Europe's European Language Portfolio is capable of supporting the implementation of language learner autonomy on a large scale. It begins by explaining what the author understands by "language learner autonomy", then introduces the European Language Portfolio and explains how it can stimulate reflective learning in which goal setting and self-assessment play a central role. It concludes by giving two practical examples that involve the learning of L2 English in Ireland, in one case by adult immigrants with refugee status and in the other by newcomer pupils in primary schools.