Purpose: The central argument in this paper is that ethical school leadership is imperative in a context of increasing performance-driven accountability. The purpose of this paper is to focus on school principals' perceptions of how they understand ethical leadership and how they lead the ethical use of data. Design/Methodology/Approach: This study utilises semi-structured interviews with six state school principals (one primary and six secondary) to explore their perceptions of ethical leadership practices; and how they balance current competing accountabilities in a context of performance-driven accountability. Findings: There were four key findings. First, principals used data to inform and direct their practices and their conversations with teachers. Second, while ethics was a central consideration in how principals' led, practising in an ethical manner was identified as complex and challenging in the current context. Third, Starratt's (1996) ethical framework proved to be relevant for interpreting principals' practices. Finally, all of the principals referred to dilemmas they faced as a result of competing priorities and all used a variety of strategies to deal with these dilemmas. Originality/Value: While there is a small body of research that explores school leaders' understandings of ethical tensions and dilemmas, there is little research that has focused on school leaders' understandings of the ethical use of data. This study, then, contributes to this area as it provides a discussion on school principals' leadership practices in the current climate driven by data use.