The cohort default rate (CDR) has worked to reduce students' risk of default, but decades of experience have also revealed weaknesses that policymakers must tackle. "Driving Down Default" outlines key priorities for strengthening the CDR to further reduce student loan default, including specific recommendations to protect against manipulation, build in greater incentives for schools to continue to meaningfully improve their CDRs, and ensure the CDR effectively targets high-risk colleges. [Key contributions for this report were provided by Debbie Cochrane and James Kvaal.]