An electroencephalographic (EEG) investigation was conducted to determine whether the pattern of hemispheric activation in females differs from that of males and whether the pattern for intellectually precocious youths differs from that of average ability youths. Electrical activity was monitored at four brain locations (i.e., frontal, temporal, parietal, and occipital lobes) over the left and right cerebral hemispheres (LH/RH). EEG recordings were taken while right-handed 13-14 year-olds of both sexes: (1) looked at a blank slide (baseline condition) and, (2) viewed pairs of chimeric faces judging which of the two was "happier" (experimental condition). At the electrophysiological level a significant difference in alpha activation between average and precocious groups was revealed. During the baseline condition, gifted youths exhibited primarily LH activation while average ability youth produced primarily RH activation. During chimeric face processing, the male gifted youth showed a distinct shift to RH processing with male average ability youth maintaining a predominantly LH activation; both female gifted and average ability youth revealed bilateral involvement of the hemispheres during face processing. Moreover, during this task, within hemisphere sex differences were found such that female hemispheric activation tended to be anteriorly localized to the frontal regions of the cortex, while for males, the activational change was seen primarily in the temporal regions. Thus, the general contention by Kimura (1983) that females use predominantly anterior locations for processing while males use posterior regions for processing is supported. At the behavioral level, during face processing, no sex or intelligence level differences were found. With both average and precocious youths choosing the left-side/neutral chimeras more often, a pattern thought to be indicative of enhanced right hemisphere (RH) arousal during the processing of facial affect. Taken in composite, these results suggest that precocity is mediated by distinctly different mechanisms in males and females.