This paper explores the use of school self-evaluation (SSE) conclusions in school leaders’ decision making regarding school management. Originating from the understanding that school management is a complex process that thrives when informed and substantiated by rigorous and contextualised information on school functioning, this study highlights that SSE processes are a valuable source of such information. The present study was conducted following a qualitative approach in which 18 school leaders (i.e., headteachers) from schools in Portugal were interviewed through semi-structured interviews to explore how they perceive SSE, and if and how they use it to make decisions in their schools. The results reveal that school leaders value SSE processes and the knowledge produced by them as a source of contextualised information that can be used to validate and legitimise decisions. Likewise, the results indicate that school leaders use the information provided by SSE to inform their decisions in collaborative and shared debates and reflection processes with their school communities. Nonetheless, the headteachers also report some constraints in decision-making processes. It is evident that school leaders rely on SSE results and information to substantiate their decisions. Although not generalisable, these results provide valuable insights into the topic and contribute to closing a gap in the literature concerning the effective use of SSE in school management and decision making.