A dancer subsystem may be used as a tension measurement or as a disturbance attenuator depending on its design. The design of a dancer subsystem to accomplish a desired result requires the development of a dynamic model for the subsystem. This paper presents the results of a generalized dynamic model of a dancer subsystem. Examples are presented to illustrate the behavior of an unwind-rewind web transport system which incorporates a dancer subsystem, and which has periodic disturbances from an out-of-round unwinding roll.