Background/Context: The importance attached to practicing data use is evident in its inclusion in federal law, competitive grant programs, state teaching license requirements, and professional development (PD) workshops around the world. Yet, practitioners and scholars have identified misconceptions clouding data use practice, questioned its utility, and suggested its discontinuation. These tensions are linked to various conceptualizations of data use, which include simple, linear, and complex, contextualized understandings. Prior research on data use as sensemaking, data use intervention components and promising practices, factors influencing data use, and using data to address equity suggest data use is a complex endeavor. Purpose/Objective/Research Question/Focus of Study: This study explored the link between teacher data use, in its many forms, and improvements in student achievement. Research Design: This study is a systematic review of 39 quantitative, qualitative, and mixed methods studies. Data Collection and Analysis: Descriptive details of each study were recorded, including the sample and its demographics; study location, length, design, and measures; school subject foci; type(s) of data used and type(s) of data strategies employed; school levels involved; and findings/results. Data use efforts also were coded for their inclusion of data use intervention components and promising practices; teacher, context, and assessment factors influencing data use; and equity practices and principles. Study results were categorized as positive, mixed, or null based on main effects, and shifts in proportions of study outcomes were noted as results were analyzed through a variety of lenses. Findings/Results: Fifteen studies identified positive relationships (38% of studies) between data use and student achievement, 10 pointed to mixed relationships (26%), and 14 shared no (or null) relationships (36%). No differences were evident when considering studies by the school levels, subject areas, and study designs involved. Studies that had positive impacts on student achievement more often than the sample overall incorporated the following elements: ongoing professional development, comprehensive data use interventions targeting multiple leverage points, multiple types of data, and intentions to use data for continuous improvement of all students. Conclusions/Recommendations: Findings demonstrate that a comprehensive framework for data use can have positive impacts on student achievement. Implications for future research and practice are provided.