This research focuses on the retention of students' algebraic understandings one year following a Grades 3-5 early algebra intervention. Participants included 1455 Grade 6 students who had participated in a cluster randomized trial. Approximately half of these students received an early algebra intervention as part of their regular instruction in Grades 3-5, while the other half received only their regular mathematics instruction. Results show that, as was the case at the end of Grades 3, 4 and 5, treatment students outperformed control students at the end of Grade 6 on a measure of algebraic understanding. This was despite the fact that treatment students experienced a significant decline in performance and control students a significant increase in performance after the intervention. An item-by-item analysis performed within condition revealed the areas in which students in the two groups experienced a change in performance. [For the complete proceedings, see ED606556.]