Individuals with autism spectrum disorder (ASD) have difficulties in many areas of social cognition including face perception. Decades of research examining face processing abilities in ASD populations have yielded equivocal results. The current thesis includes a series of experiments intended to clarify the nature of the face processing deficits seen in ASD. In Study 1 I examined norm-based coding of facial identity in adults with ASD. I measured identity aftereffects in adults with and without ASD and found no significant group differences. In Study 2 I examined simple (Experiment 1) and opposing (Experiment 2) figural aftereffects for male and female faces and found no significant group differences as adults with ASD. In Study 3 I examined perceptual strategies employed by adults with ASD when processing emotional facial expressions and found that adults with ASD employ a rule-based strategy. Finally, in Study 4 I examined what drives face processing deficits in adults with ASD; deficits in processing emotional information in faces or a deficit in processing socially complex information in faces. I found that adults with ASD had a deficit in discriminating basic and complex emotional facial expressions, suggesting that emotion-perception demands are associated with poor face processing in ASD. The results of the studies demonstrate that adult with ASD show typical perceptual mechanisms underlying face perception, use an atypical perceptual strategies when processing facial expressions, and have a specific deficit in processing emotional expressions. / Thesis / Doctor of Philosophy (PhD)