The purpose of this study was to evaluate the difference in grading of objective structured clinical examinations (OSCEs) at Harvard School of Dental Medicine (HSDM) by full-time faculty examiners, part-time faculty examiners, and postgraduate resident examiners. The OSCE is an evaluation of clinical competence and is used as a multidisciplinary examination at HSDM. Two examiners are selected for each of ten disciplines. Evaluators meet to review the case before the OSCE is given, and faculty examiners are given the opportunity to write exam questions based on the students' expected level of knowledge and ability. All examiners also meet on the day of the OSCE to review the case and discuss relevant issues. Students are randomly assigned to examiners and meet with one examiner at a time in each discipline during the examination. Analysis of OSCE scores on four exams given to HSDM students between 2012 and 2013 suggests that part-time faculty members tended to score students significantly higher than full-time faculty members or postgraduate residents. This may be a result of reduced contact time between students and the part-time faculty although it may also point to a need for more efforts in calibration of the part-time faculty members who take part in the OSCE.