Considering the early role of human faces as compelling stimuli for typically developing newborns and considering the emergence of sophisticated face recognition skills by six months in typical development, it is very likely that face processing in autism spectrum disorder (ASD) is affected from the first months of life. This project aims to characterize the emergence of face processing abnormalities in infants with ASD by prospectively following, from 3 months to 36 months of life, 160 infants at high risk for developing ASD due to a genetic liability (i.e., by having an older sibling with ASD). At 36 months, clinical diagnosis of the high-risk population will afford the division of the population into three groups: 1) siblings with ASD; 2) Non-affected siblings; and 3) siblings with various developmental delays but without ASD features. Developmental changes in face processing skills will be compared against 40 low-risk, typically developing infants. It is expected that the patterns in localization of faces, focused attention towards faces, attention capture by faces, and face scanning and recognition, will, in combination, highlight the developmental divergence in high-risk and low-risk children and correlate with worsening autistic symptoms. The primary goals of this research are to identify the type of primary impairments in face processing and to understand the developmental trajectories of face processing abnormalities in the earliest stages of ASD. This will inform early diagnosis (through identification of potential early indicators of risk for ASD), treatment (though identification of pivotal target skills), and theory (through enhancing understanding of mechanisms underlying abnormalities in face perception in ASD).