As part of the 2010 economic stimulus, a $55 million "Investing in Innovation" (i3) grant from the US Department of Education was awarded to scale up Reading Recovery across the nation. This paper presents the final round of results from the large-scale, mixed methods randomized evaluation of the implementation and impacts of Reading Recovery under this i3 Scale-Up. Over 10,000 low performing first-grade students from more than 1,000 schools participated in this study from 2010-2015. The evaluation design for the i3 scale-up of Reading Recovery includes a rigorous experimental research design (i.e., a multi-site randomized controlled trial) that supports strong causal inferences about program impacts, coupled with mixed methods descriptions of program implementation and contextual factors. Short-term impacts on students' reading performance are estimated by comparing mid-year reading achievement of students randomly assigned to participate in reading recovery at the beginning of first grade to students randomly assigned to the control condition. The consistently large positive impacts of Reading Recovery under the i3 scale-up suggest that this relatively large investment has led to substantial improvements in the reading performance of many thousands of students across the nation. In addition, results from the mixed-methods implementation evaluation revealed numerous programmatic and contextual factors that can support or hinder implementation of Reading Recovery by individual schools and may explain variation in impacts across sites.