The purpose of this study is to examine the interplay of children's temperamental attention and activity (assessed when children were 4-and-a-half years old) and classroom emotional support as they relate to children's academic achievement in third grade. Particular focus is placed on the moderating role of classroom emotional support on the relationship between temperament (attention and activity level) and academic achievement. Regression analyses indicated that children's attention and activity level were associated with children's third grade reading and mathematics achievement, and classroom emotional support was associated with children's third grade reading and mathematics achievement. In addition, classroom emotional support moderated the relation between children's attention and reading and mathematics achievement, such that attention mattered most for reading and mathematics achievement for children in classrooms with lower emotional support. Findings point to the importance of understanding how children's temperament and classroom emotional support may work together to promote or inhibit children's academic achievement. (Contains 2 figures and 5 tables.)