Reading Recovery (RR) is a short-term, one-to-one intervention designed to help the lowest achieving readers in first grade. This article presents first-year results from the multisite randomized controlled trial (RCT) and implementation study under the $55 million Investing in Innovation (i3) Scale-Up Project. For the 2011-2012 school year, the estimated standardized effect of RR on students' Iowa Tests of Basic Skills (ITBS) Total Reading Scores was 0.69 standard deviations relative to the population of struggling readers eligible for RR under the i3 scale-up and 0.47 standard deviations relative to the nationwide population of all first graders. School-level implementation of RR was, in most respects, faithful to the RR "Standards and Guidelines," and the intensive training provided to new RR teachers was viewed as critical to successful implementation.