The authors analyze the challenges to using academic measures (MCAT scores and GPAs) as thresholds for admissions and, for applicants exceeding the threshold, using personal qualities for admission decisions; review the literature on using the medical school interview and other admission data to assess personal qualities of applicants; identify challenges of developing better methods of assessing personal qualities; and propose a unified system for assessment. The authors discuss three challenges to using the threshold approach: institutional self-interest, inertia, and philosophical and historical factors. Institutional self-interest arises from the potential for admitting students with lower academic credentials, which could negatively influence indicators used to rank medical schools. Inertia can make introducing a new system complex. Philosophical and historical factors are those that tend to value maximizing academic measures. The literature identifies up to 87 different personal qualities relevant to the practice of medicine, and selecting the most salient of these that can be practically measured is a challenging task. The challenges to developing better personal quality measures include selecting and operationally defining the most important qualities, measuring the qualities in a cost-effective manner, and overcoming "cunning" adversaries who, with the incentive and resourcefulness, can potentially invalidate such measures. The authors discuss potential methods of measuring personal qualities and propose a unified system of assessment that would pool resources from certification and recertification efforts to develop competencies across the continuum with a dynamic, integrated approach to assessment.