Despite the increased worldwide acknowledgment of the importance of teachers' use of formative and/or summative assessment data to improve teaching and learning, empirical research on its impacts on student learning is sparse. Even more so is the lack of studies on the best ways for school leaders to develop teachers' capacity. Teachers generally have low efficacy in using student data to inform their day-to-day instructions. Teachers lack the basic skills to understand, interpret, and analyze data, develop instructional strategies based on data, and implement research-based instructional strategies in classrooms to address the weaknesses reflected from data analysis results. Any gap in this chain of instructional actions would lead to ineffective teaching and learning in classrooms. This study synthesizes research located from on-line databases on teachers' data use conducted in the last 14 years and examines the nature, impacts, and shapers of teachers' use of student formative and/or summative assessment data to improve teaching and learning. This review provides a much-needed guide to school leaders and policy makers in the USA, as well to other jurisdictions that want to make evidence-based decisions in the hopes of improving student learning and teachers' capacity in data use.