Although pre-ratio pausing is a characteristic feature of fixed ratio (FR) schedules of reinforcement, pausing reduces the rate at which reinforcement is earned. To determine whether FR pausing can be altered, 7 rats were studied with procedures in which long pauses were punished with time-out from reinforcement. A general finding was that pausing is modifiable. However, tendencies to pause were highly resistant to change, and for some animals under some conditions efforts to reduce pausing were unsuccessful. Moreover, despite the fact that reduced pausing was accompanied by increased reinforcement rates, long pauses resumed when the punishment contingency was removed. Two sets of factors were proposed as contributors to these mixed results: the relatively small gain in reinforcement rates that accompanied reduced pausing, and the possible status of pre-ratio pausing as a form of elicited, rather than operant, behavior.