Viewpoints on different assessment systems used in many educational bureaucracies are diverse and continually evolving. Schools are tasked with translating those reforms' philosophies and principles into school-based assessment practices. However, it is unclear from research evidence what approach and factors best support the implementation of assessment reforms. To guide school leaders to design and implement school-based assessment reforms, there is a need to develop coherent knowledge of how school-based assessment reforms are implemented. We reviewed the literature on school-based assessment reforms using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. From a synthesis of the 28 articles included, we reported what approaches are used to implement assessment reforms and what factors influenced their implementation. Furthermore, we have proposed a framework that defines the political, cultural, structural, chronological, paradigmatic, and technological perspectives that need careful attention when implementing assessment reforms in schools.