This paper presents an exploratory case study of teacher agency for social justice in a primary school in Scotland. Mixed methods and tools, including a questionnaire, interviews, observations and logs, were used to explore four aspects of agency: sense of purpose, competence, autonomy, and reflexivity with regard to issues of social justice. Teachers perceive agency for social justice as an important part of their professional role. Relationships with students, families and others, and participation in decision-making are seen as key to promoting social justice, and as features of structural environments that enable agency. Methodological challenges for future research are discussed.