Siblings of children with autism have a likelihood of developing autism that is nearly twenty times higher than that of the general population. Studying potential biologic predictors of autism early in life before a behavioral diagnosis can be made, and then determining which of these children ultimately merit a diagnosis of autism, can therefore provide important information about early predictors of autism. EEG is an ideal test for potentially predicting autism for several reasons. First, prior studies suggest that connections between neurons in the brain are different in children with autism, and that these connections can be assessed using EEG. Additionally, EEG is noninvasive, does not require sedation, and allows evaluation of brain activity without a child’s active behavioral participation. This study will evaluate the use of EEG-based brain connectivity as a predictor of future autism diagnosis by determining if infants with certain early EEG features are more likely to go on to be diagnosed with autism at age 3. Ultimately, this study has potential to inform future development of a clinically useful, easily administered, cost effective early screening test for autism.