Despite recent growth in research highlighting the potential of teacher-child relationships to promote children's development during the early years of school, questions remain about the importance of these relationships across elementary school. Using data from the NICHD Study of Early Child Care (N = 1,364), this study examines between- and within-child associations between teacher-child relationship quality and children's academic achievement and behavior problems from kindergarten (ages 4-6 years) through 5th grade (ages 9-11 years). Results suggest that increases in teacher-child relationship quality are associated with improvements in teacher-reported academic skills and reductions in behavior problems consistently throughout elementary school. As children progressed from kindergarten through fifth grade, the importance of teacher-child relationship quality is unchanging.