Clinical investigations have found that lesions of the right cerebral hemisphere can disrupt face perception. Much less is known about the determinants of facial discrimination in healthy adults, although age-related differences in many cognitive abilities have been shown to correlate with simple processing speed and variation in regional brain volumes. In this study, 174 healthy adults between the ages of 20 and 92 were asked to match pictures of unfamiliar faces. After their performance was regressed on age, sex, education, and perceptual comparison speed, adding terms for frontal lobe volume, nonfrontal volume, and ventricle-to-brain ratio (VBR) derived from magnetic resonance imaging improved the model and accounted for 35% of the variance in facial discrimination. VBR and processing speed alone accounted for nearly 34% of the variance. These findings suggest that both normal atrophic brain changes and decreases in processing speed contribute to individual differences in facial discrimination.