Some computer tapes exhibit excessive friction after repeated use or through use in some tape drives. An objective of this study was to develop methodology for monitoring the physical and bulk-chemical changes of tapes during wear and correlating any changes with increases in friction. From simulated head-tape interface tests and tape-drive tests, we have generally observed an increase in friction during tape wear. Bulk-chemical properties were monitored and did not change during wear. Changes in surface smoothness were not found significant enough to account for the increase in friction, but a noticeable increase in the real area of contact was measured and indicated mechanical and/or chemical changes in the tape surface. Techniques for monitoring surface chemistry need to be developed before specific changes in tape surface that lead to an increase in friction can be fully understood.