This year signifies two key milestones in the GradNation campaign to raise high school graduation rates. First, the release of the 2015 federal graduation rate data marks five years since states began reporting the Adjusted Cohort Graduation Rate (ACGR). The ACGR, for the first time, created a common formula for collecting graduation rate statistics across states and provides data on individual student subgroups down to the school and district levels. With five years of ACGR data, students continue to graduate at higher and lower rates and how this varies by state, and where graduation rate gaps are closing and persisting between student subgroups. Second, there are now just five years of federal graduation rate data reporting between now and the culmination of the GradNation goal to raise high school graduation rates to 90 percent by the Class of 2020. This report examines areas of concern in high school graduation rate reporting, including measurement errors, cases of schools and districts gaming the system, and issues around lowering diploma standards, as well as other areas of progress and remaining challenges on the path to 90 percent. Seventeen appendices are included. [For the 2016 report, see ED572731.]