The need for research on how social justice is enacted in schooling is pressing. A significant gap - large by international standards - is now apparent between the academic achievements of different groups of Australian school students. While some score at levels among the best in the world on international literacy and numeracy tests, other students are part of a long tail of under-achievement. Their differences in achievement correlate with their differences in socioeconomic status. To date, social justice research in education has tended to focus on the outcomes for students of policies and programs (their curricula, pedagogies) and of belief systems (of policy makers, teachers). In contrast, this paper introduces a new analytical category - social justice dispositions - to further advance understandings of how educational advantage and disadvantage are enacted through teachers' practices. Informed by the social theory of Bourdieu, social justice dispositions are understood as the tendencies, inclinations, and leanings that provide un-thought or pre-thought guidance for socially just practice, which operate between belief and practice, distinguishing between what is said and done. For example, dispositions explain why some teachers tend to favour (e.g. spend more time interacting with) boys over girls, even though they believe in gender equality (Sadker & Sadker 1995). The paper begins from the premise that dispositions are revealed in actions (Bourdieu & Wacquant 1992). Hence, teachers' work, specifically their pedagogic actions, is understood as the vehicle through which teachers' social justice dispositions can be identified. Significantly, the paper extends Bourdieu's account of pedagogic work by conceptualising it as an 'activity system' (Engeström 1987). That is, teacher-agents are disposed to do certain things in certain social/material circumstances. Their dispositions operate as a 'strategy-generating principle enabling agents to cope with unforeseen and ever-changing situations' (Bourdieu 1977: 72); orienting actions without strictly determining them. By drawing on new developments within cultural-historic activity theory to examine how different contextual conditions contribute to different forms of practice, the paper extends Bourdieu's work in a way that identifies possibilities within existing conditions for concrete/practical change and transformation within education systems.