Over the past several decades, the student population in the United States has grown more diverse by factors including race, socioeconomic status, primary language spoken at home, and learning differences. At the same time, learning sciences research has advanced our understanding of learner variability and the importance of grounding educational practice and policy in the individual, rather than the fiction of an average student. To address this gap, Learner Variability Project (LVP) distills existing research on cognitive, social and emotional, content area, and background Learner Factors that affect learning in various domains, such as reading and math. In conjunction with the development process, Learner Positioning Systems (LPS) researchers worked with ReadWorks to design studies to assess the impact of the newly implemented features on learner outcomes.