Engaged in the evaluation of LDC tools since June 2011, UCLA's National Center for Research on Evaluation, Standards, and Student Testing (CRESST) is using multiple data sources and a quasi-experimental design to examine LDC implementation and impact in two cohorts of schools in two large, urban school districts. This report presents the results on implementation of LDC in the large urban school district on the West Coast during the third year of the intervention, and the impact of the program across multiple years. Findings from both participant surveys and analyses of student outcomes reveal positive results for the LDC intervention. Analysis of student outcomes provided evidence of the program's effectiveness and confirmation for participants' positive views. Quasi-experimental analyses demonstrated a statistically significant positive impact of LDC as practiced by middle school teachers with 2 years of program experience across two cohorts of schools and teachers. A statistically significant positive impact was also found for Cohort 2 middle schools after just one year of implementation. [For the 2017-2018 report, see ED600053.]