This study examines the association between approaches to learning (ATL) and reading and mathematics achievement using U.S. data from the Early Childhood Longitudinal Study of the Kindergarten Class of 2010-2011. Within-grade and across-grade analyses are conducted using individual fixed-effects that control for time-invariant effects and minimize estimation bias. Results from within-grade analyses indicate that ATL is positively related to reading and mathematics achievement in kindergarten, first and second grade. Results from across-grade analyses demonstrate sustained positive associations between ATL and reading and mathematics achievement in grades K-4. Lagged ATL effects are manifested, especially of adjacent prior grades, a finding that extends prior findings and offers a novel perspective in understanding the long-term relationship between ATL and reading and mathematics achievement. The relationship between ATL and achievement is stronger in reading than in mathematics. These findings indicate the importance of ATL in improving reading and mathematics achievement in early grades.