This paper reports on an interpretive study in which 25 elementary principals were asked about their assessment knowledge, the use of large-scale assessments in their schools, and principals’ perceptions on their roles with respect to large-scale assessments. Principals in this study suggested that the current context of large-scale assessment and accountability has resulted in their roles being redefined. In particular, they suggested that it is the principal’s role to teach other staff members about assessment, to advocate for assessment, and to organize and manage data. We argue that these emerging roles have the potential to redefine instructional leadership in schools.