The purpose of this study was to understand the implementation and impact of the New Teacher Center's (NTC) 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. 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. A previous version of this report was published in December 2020. This report provides updated information for review under WWC version 5.0 standards. See "2025 Report Updates" for a list of the changes made. 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. The following are appended: references; the implementation fidelity matrix; survey item text and scale properties; supplementary, exploratory, and sensitivity analyses; and additional information for What Works Clearinghouse review.