The Institute of Medicine report on dental education in the mid-1990s called specific attention to the need for authentic assessment of student progress and outcomes. This corresponded with the advent of competency-based dental education, resulting in recognition of the need for new methods to assess dental students knowledge, skills, and values in the context of beginning independent dental practice. The portfolio approach to assessment uses a rich collection of cumulative evidence from multiple sources in ways that address this need. Because students take some responsibility for maintaining their portfolios, the competency of reflective critical thinking can also be assessed by means of portfolios.