This study examined age differences in the factor structure of EEG using a 128-electrode system. Running EEG records were obtained from healthy younger and healthy older adults before, during, and after they performed a 13-minute Continuous Performance Task. Factor analyses were conducted on each five-second segment of EEG data by treating the voltages obtained at each electrode site as variables and each measurement epoch as a case. Results showed that the EEG records of older adults yielded significantly more factors than those of younger adults in every task condition. In addition, eigenvalues for the first common factor derived from EEG data sets were significantly larger in the EEG recordings of younger adults than older adults. The results are interpreted to indicate a greater degree of complexity in the spatial distribution of EEG activity in older adults, possibly reflecting an age-related decrease in the degree of coordination among cortical areas.