We have given a group of 56 Massachusetts Institute of Technology (MIT) seniors who took mechanics as freshmen a written test similar to the final exam they took in their freshman course as well as the Mechanics Baseline Test (MBT) and the Colorado Learning Attitudes about Science Survey (CLASS). Students in majors unrelated to physics scored 60% lower on the written analytic part of the final than they would have as freshmen. The mean score of all participants on the MBT was insignificantly changed from their average on the posttest they took as freshmen. However, the students' performance on 9 of the 26 MBT items (with 6 of the 9 involving graphical kinematics) represents a gain over their freshman posttest score (a normalized gain of about 70%), while their performance on the remaining 17 questions is best characterized as a loss of approximately 50% of the material "learned" in the freshman course. On multiple-choice questions covering advanced physics concepts, the mean score of the participants was about 50% lower than the average performance of freshmen. Although attitudinal survey results indicate that almost half the seniors feel the specific mechanics course content is unlikely to be useful to them, a significant majority (75%-85%) feel that physics does teach valuable problem solving skills, and an overwhelming majority believe that mechanics should remain a required course at MIT. (Contains 11 tables and 10 figures.)