As the twelfth in the Completing College series, this report updates the six-year college completion rates nationally and by state, by tracking the enrollment and completion outcomes for the fall 2017 cohort of beginning college students through June 2023. The report also features national eight-year completion outcomes for fall 2015 through June 2023. The national completion rate measures the performance of the entire higher education system. It counts all students who enter postsecondary education for the first time each fall, enrolling full-time or part-time at two-year or four-year institutions, and completing at any U.S. degree-granting institution. It includes those who complete after transfer, not just completions at the starting institution. Thus, the results more fully capture today's students' success, which increasingly involve mobility across institutions, re-entry after stop-out, and changes in enrollment intensities. A longitudinal data dashboard accompanies this report and offers detailed six-year and eight-year completion outcomes by cohort year across starting institution sectors and student backgrounds, enabling national and state-level comparisons through interactive visualizations and analysis tools.