Fully two-thirds of U.S. fourth graders are not reading proficiently, national assessments show. The numbers are even more dire for students from low-income families: 80 percent of them have not reached proficiency. Amid the search for solutions -- whether through better instruction, improved curriculum or third-grade retention policies -- educators and families often overlook the potential to raise achievement by improving student attendance. This brief summarizes a growing body of research which documents how many youngsters are chronically absent, meaning they miss 10 percent or more of the school year due to excused or unexcused absences. The research also shows how these missed days as early as preschool translate into weaker reading skills.