Purpose To examine the relationship between graduates' performances on a prototype of the National Board of Medical Examiners' Step 2 CS and other undergraduate measures with their residency directors' ratings of their performances as interns. Method Data were collected for the 2001 and 2002 graduates from the study institution. Checklist and interpersonal scores from the prototype Step 2 CS, along with United States Medical Licensing Examination (USMLE) Step 1 and 2 scores and undergraduate grade-point average (GPA), were correlated with residency directors' ratings (average score for six competencies, quartile ranking, and isolated interpersonal communication competency score). Stepwise linear regression was used to identify the best outcome predictors. Results Quartile ranking was more highly correlated with GPA than Step 2 CS prototype interpersonal score, USMLE Step 2 score, USMLE Step 1 score, and Step 2 CS prototype checklist score. The average score on the residency director's survey was more highly correlated with GPA than USMLE Step 2 score, USMLE Step I score, Step 2 CS prototype interpersonal score, and Step 2 CS prototype checklist score. The best predictors for both quartile ranking and average competency score were GPA and Step 2 CS prototype interpersonal score (R-2 = 0.26 and 0.28). Conclusion Both scores from the Step 2 CS prototype significantly correlated with the interns' quartile ranking and average competency score. Only GPA and Step 2 CS prototype interpersonal score accounted for most of the variance of performance in the regression model.