<p>After participating in external standardized assessments, schools are typically presented with performance feedback intended to inform self-evaluation. In the context of the Flemish national assessments, we conducted a qualitative study in which we investigated which causes teachers and school leaders invoke for their school's results as presented in an authentic school feedback report. We examined the locus of causality of these attributions and explored patterns according to participants’ work role and perceived favorability of the feedback. Data were collected through 22 online semi-structured interviews and subjected to a framework analysis. Attributions at the school, class, student, and test levels are discussed. In line with previous research, we find that school performance is attributed to external factors to a great extent. We also find that educational professionals make sense of school performance feedback from their own frame of reference. School leaders apply a policy outlook, while teachers reflect more on the input from students. Reservations about (the design of) the assessment emerge primarily to explain negative results. The finding that teachers and school leaders (even within schools) place different emphases to interpret the (same) outcomes highlights the importance of collective sensemaking. The observation that most participants mentioned a whole range of factors illustrates that people see learning outcomes as the product of different building blocks, but also that it is not easy to formulate a straightforward and actionable diagnosis. Implications for practice and suggestions for further research are addressed.</p>