This study examines the association between classroom order in 4th and 5th grades and student achievement growth over a school year. A three level transactional model tested the effects of classroom order on students' rates of growth in math and reading during the school year controlling for starting achievement levels, student risk factors, and classroom poverty. Classroom order influenced students' rates of math and reading growth and accounted for a significant portion of variance in student achievement trajectories above and beyond student-level risk factors. Cross-level analyses identified the moderating effects of classroom order on achievement growth for at-risk students with higher levels of classroom order predicting greater rates of math achievement growth among disadvantaged minority students. (Contains 5 tables and 1 figure.)