The aim of this study was to explore the results of and conditions for systemiclarge-scale school improvement. Through a multi-level analysis and a theoreticalframework inspired by organization- and sensemaking-oriented theories, the studyexamines how a Swedish large-scale school improvement program, “Collaborationfor the Best School Possible,” played out in two Swedish municipalities. Schoolactors at four organizational levels (at the National Education Agency, Local Education Authority, school leader, and teacher levels) in the two municipalities wereinterviewed. Because these school actors’ sensemaking is linked to different aspectsof the national largescale improvement program, the analysis shows a variation inthe strengthening of the couplings between these organizational levels. The different nature of the couplings affected the implementation process and the results ofthe program. While the national large-scale program seemed to have contributed toan improvement in the schools’ quality assurance systems and leadership practices,there were difficulties in maintaining general and sustainable changes in schools’instructional practices. The conclusion of the study was that, even if a nationallarge-scale school improvement program is well designed and backed up with manyresources, it must be perceived as legitimate among the local school actors at thedifferent organizational levels. This points to the importance of managing the balance between top-down efforts and visions and local professional knowledge andexperience.