Educator performance evaluation systems are a potential tool for improving student achievement by increasing the effectiveness of the educator workforce. For example, recent research suggests that giving more frequent, specific feedback on classroom practice may lead to improvements in teacher performance and student achievement. This report is based on a study that the U.S. Department of Education's Institute of Education Sciences conducted on the implementation of teacher and principal performance measures that are highlighted by recent research, as well as the impact of providing feedback based on these measures. As part of the study, eight districts were provided resources and support to implement the following three performance measures in a selected sample of schools in 2012-13 and 2013-14: (1) Classroom practice measure; (2) Student growth measure; and (3) Principal leadership measure. Within each district, schools were randomly assigned to implement the performance measures (the treatment group) or not (the control group). No formal "stakes" were attached to the measures--for example, they were not used by the study districts for staffing decisions such as tenure or continued employment. Instead, the measures were used to provide educators and their supervisors with information regarding performance. Such information might identify educators who need support and indicate areas for improvement, leading to improved classroom practice and leadership and boosting student achievement. This is the second of two reports on the study. The first focused on the first year of implementation, describing the characteristics of the educator performance measures and teachers' and principals' experiences with feedback. This report examines the impact of the two-year intervention, as well as implementation in both years. The main findings are: (1) The study's measures were generally implemented as planned; (2) The study's measures provided some information to identify educators who needed support, but provided limited information to indicate the areas of practice educators most needed to improve; (3) As intended, teachers and principals in treatment schools received more frequent feedback with ratings than teachers and principals in control schools; and (4) The intervention had some positive impacts on teachers' classroom practice, principal leadership, and student achievement. This report is a summary to the full report. [For the full report, "The Impact of Providing Performance Feedback to Teachers and Principals. NCEE 2018-4001," see ED578873. For the first year report, "Early Implementation Findings from a Study of Teacher and Principal Performance Measurement and Feedback: Year 1 Report. NCEE 2017-4004," see ED569983. For the first year report executive summary, "Early Implementation Findings from a Study of Teacher and Principal Performance Measurement and Feedback: Year 1 Report. Executive Summary. NCEE 2017-4003," see ED569982.]