Assessment plays a pivotal role in the school improvement in ensuring its effectiveness, continuity, and impact. This session is designed to explore the role of assessments and the use of data in the continuous school improvement process, and examines assessment practices, professional collaboration and assessment literacy that contribute to positive changes in schools. The chapter also highlights the impact of effective assessment practices in improving schools through a study of four private schools in the Emirate of Sharjah, United Arab Emirates that made significant improvement in their level of educational quality by adopting effective assessment processes.