The definition of social justice in education is neither universally agreed upon nor has it remained static over time. Concepts of fairness, social recognition, diversity, inclusion, and antibias are among the main concepts that constitute how scholars think about, and educators practice, social justice in their work. Although conceptualizing social justice and the ways social justice looks in the field do not always align, they do inform each other, and university educator preparation programs provide a unique bridge between theory and practice. Although there have been notable attempts to co-opt and limit the social justice lexicon, over time ideas about what social justice means have grown to be more eclectic, not more exclusive. Moreover, initially disparate ideas about justice have found connections in philosophy and practice, and inform each other in interesting ways that help guide educators in how to conceive of, engage in, and measure transformative social justice action. This chapter traces the tensions, collaborations, and evolution of how social justice in education has been defined over time and across far-flung corners of the education enterprise. The primary questions this work considers are: (1) How do scholars conceptualize and advocate for social justice in theory and practice? (2) How do practitioners engage in the practice of social justice? (3) Where do practitioners draw their theoretical understanding of, and ideas for, practicing, social justice?