The paper "Thinking of, Knowing, and Doing Social Justice Leadership: Principals' Perspectives" explores the understanding and practice of principals regarding social justice leadership. The study adopts phenomenography as its methodology and presents findings gleaned from the semi-structured interviews of 11 principals in Trinidad and Tobago. Findings indicate that principals were generally unaware of a social justice leadership orientation, but values of fairness and equity, for instance, were common in their understandings. Social justice leadership roles were conceptualized as multifaceted, difficult and requiring strategy and caution, but emphasized a need for self-investment and collaboration. It was found that principals' unclear conceptualizations translated into guesswork when practicing social justice leadership from which emerged unique ways of 'doing' social justice. Findings point to the need to place social justice atop Trinidad and Tobago's school improvement agenda.