This chapter reviews autonomy and agency as related to second language (L2) learner and teacher psychology. It discusses the significance of the two constructs in understanding the personal, yet socially mediated nature of L2 learning and teaching processes. Psychology and education seem to be the main disciplines that have influenced developments in fostering on autonomy in second language acquisition (SLA). Research on autonomy has typically been conducted on the initiative of a teacher or groups of teachers working in their specific educational contexts and with their specific groups of students. Compared to agency, autonomy has had a much longer history in SLA, and it has been researched much more widely, yet still with a heavy emphasis on learners. Whereas research on agency has focused on contextually enacted ways of participating, research on autonomy has focused on the developing degree of independence and control of that participation.