The 'default mode network' is a set of brain regions showing correlated, low-frequency activity during rest. It includes the posterior cingulate/precuneus, medial prefrontal cortex, and bilateral inferior parietal cortex. Earlier studies have characterized this network using either region of interest-based correlation analyses or data-driven techniques; however, there is some disagreement over which method is superior. We conducted both types of analysis on a large (N=40) data set and also investigated age and sex differences in the network. Both region of interest-based analyses and independent component analysis identified the default mode network. Age and sex differences were small and there was less agreement between analytic techniques regarding age and sex effects than regarding default mode network structure.