This study uses a three-level model (within-student, between-student, and between-classroom) to examine the effects of 4th and 5th grade classroom environments on student achievement trajectories during the school year. Between-classroom differences in teacher warmth and classroom order were tested as predictors of student rates of achievement growth, controlling for classroom poverty as well as student characteristics. Classroom order and poverty added incrementally to students' rates of achievement growth when student level demographic and behavioral effects were included in the model. Cross-level analyses identified the moderating effects of classroom environment on achievement growth for at-risk students with higher levels of classroom order promoting greater rates of math achievement growth among disadvantaged minority students. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]