Beginning teachers enter a profession that places particularly challenging demands on novice practitioners. The New Teacher Center's (NTC) induction model provides intensive, instructionally focused coaching to teachers during their first two years in the classroom, in-depth training for induction mentors, a suite of tools to guide coaching cycles, and capacity-building for district leaders to sustain induction mentoring programs after NTC's direct involvement in the district ends. With funding from a U.S. Department of Education Investing in Innovation (i3) scale-up grant, NTC tested strategies for scaling its validated induction model to 301 schools in five school districts serving high proportions of students of color and students from low-income households. NTC adapted its model to support district adoption at scale, including an option for deploying part-time, school-based mentors, reduced requirements for mentor training, and online training and video-sharing tools. SRI's evaluation of the implementation and impact of NTC's i3 scale-up grant employed a cluster-randomized controlled trial design with schools as the unit of randomization. All first-year teachers in randomized schools were included in the study. Treatment teachers received induction supports from NTC-trained mentors, while control teachers received the supports provided by their districts under business-as-usual conditions. The evaluation examined fidelity of implementation to the model as designed, the contrast between the induction supports in the treatment and control conditions, and impacts on three key outcomes: 1) teachers' classroom practice as measured by the Danielson Framework for Teaching, 2) student achievement on state standardized assessments in mathematics and English Language Arts (ELA) in grades 4 through 8, and 3) teacher retention within district. NTC's induction model was not implemented with adequate fidelity in any of the five sites according to thresholds set by NTC, and the mentoring received by NTC treatment teachers was not substantially different in key respects from the mentoring received by control teachers. There were no statistically significant impacts of the model as implemented on overall teacher practice, student achievement, or teacher retention. Exploratory findings suggest conditions under which NTC might see a greater impact. There was a positive correlation between students' mathematics achievement and mentoring that met NTC's fidelity thresholds for frequency and duration, as well as between mathematics achievement and mentoring that met NTC's expectations for instructional focus. NTC induction supports also had a positive impact on student ELA achievement in schools with higher proportions of historically underserved students. These findings indicate the importance of ensuring high-quality implementation of a program. Under the i3 scale-up grant, NTC attempted to adapt its model for scaling, but the partner districts failed to fully implement key components and mediators as intended. There is evidence that the model has promise when fully implemented, particularly in schools with higher proportions of historically underserved students, but without further research this evidence is simply suggestive.