Fluctuations in cognitive task performance in older individuals have been reported. To examine intraindividual variability as a function of practice, 34 younger and 34 older female participants, aged 20-30 years and 70-82 years, respectively, performed a reading span task 16 times over four sessions. Each individual's recall accuracy was analyzed over the practice trials. It was found that intraindividual variability occurred more frequently in older than younger individuals, and that fluctuations were more frequent in mid to later trials of practice. These findings were interpreted within a resource theory framework as evidence for age-related inefficient cognitive processing with practice. (Contains 1 table and 2 figures.)