Younger siblings of children with autism (Sibs-ASD) are at risk for the development of an Autism Spectrum Disorder (ASD) or subclinical social and cognitive deficits better known as the Broader Autism Phenotype (BAP).The current study utilized a multi-level approach to examine executive attention and social competence in preschool-aged Sibs-ASD and a comparison group of age-, sex-, and Verbal IQ-matched younger siblings of children without autism (Sibs-COM). Forty-two participants (24 Sibs-ASD, 18 Sibs-COM) completed a modified version of the Children's Attention Network Task (ANT), with electroencephalograph (EEG) collected simultaneously, and a peer interaction paradigm with an unfamiliar peer.Overall, Sibs-ASD and Sibs-COM displayed comparable performance on behavioral indices of the Children's ANT, P3 amplitude and latency, and measures of observed social functioning. Surprisingly, Sibs-ASD displayed a reduced (less negative) N2 amplitude and shorter N2 latency, most evident at Fz compared to FCz, a finding not observed in Sibs-COM. Furthermore, on a parent-report index of social functioning, Sibs-ASD reportedly displayed greater social impairments than Sibs-COM. Interestingly, post-hoc analyses indicated that differences in N2 amplitude and social functioning were most apparent between affected Sibs-ASD and Sibs-COM. Therefore, results of this study provide support for social and cognitive deficits consistent with theories of the BAP.