Individual differences in behavior are associated with changes in the correlation of neural activity between brain areas. Such differences in 'functional connectivity' are thought to reflect individual differences in brain structure that alter the flow of neural activity between regions. Here, in contrast, we show that individual differences in functional connectivity and behavior can be explained by differences in how frequently an individual expresses distinct cortex-wide spatiotemporal patterns of neural activity. This suggests variability in sampling of cortex-wide neural dynamics may underlie individuals' unique behavioral phenotypes.