Academic undermatching--students enrolling in colleges that are less academically selective than those for which they qualify--is a barrier hindering college degree attainment. Given the many reasons students undermatch, this phenomenon is likely to continue; yet, we know little about the characteristics that may be related to degree attainment for this population of students. Utilizing the ELS: 2002 national dataset, we developed an operationalization of undermatch and then applied this operationalization to the BPS: 04/09 national dataset (N = 11,260). Using logistic regression methods, we identified institutional and student characteristics that are associated with degree attainment for undermatched students. Starting at a 4-year institution, completing at least precalculus, having at least one parent with a college education, being female, and being socially and academically integrated into the institution were positively associated with degree attainment. Our results emphasize the critical influence of nonacademic factors on degree attainment for undermatched students.