Data- driven decision making DDDM in school settings is often guided and influenced by various sources of data that assist in improving students' outcomes. School principals as the main educational leaders, play a pivotal role in DDDM using the available school data. Semi-structured interviews with 24 school principals were conducted to investigate the school principals' perceptions of the role of the school Performance Improvement Unit PIU in applying DDDM in Kuwait's schools. This paper uses the Kuwaiti Ministry of Education's framework and the Mandinach et al. (A theoretical framework for data-driven decision making. In: Annual meeting of the American Educational Research Association, San Francisco, 2006) model as a background to explain the application of DDDM in government centralized schools. Practical implications are provided to help policymakers develop DDDM in schools.