To estimate the long-term effects of the Reading Recovery® intervention, a regression discontinuity design (RD) was implemented in a randomly selected sample of Reading Recovery schools during each year of the federally-funded i3 Scale-Up external evaluation (2011-2015) and also in one additional cohort during the 2016-2017 school year. Long-term outcomes were measured by collecting scale scores on state achievement tests in reading or English language arts (ELA) that were administered to students during 3rd and 4th grades (2013-2019). We were able to record and link 3rd grade state test score data in reading/ELA for 9,879 students, and 4th grade state test data for 6,345 students. Results suggest that the long-term impact of Reading Recovery on students' reading/ELA test scores in 3rd and 4th grades is statistically significant and substantially negative; students who participated in Reading Recovery in first grade had 3rd and 4th grade state test scores in reading/ELA that were, on average, 0.19 to 0.43 standard deviations (about one-half to one full grade level) below the state test scores of similar students who did not participate in Reading Recovery.