The Infant Brain Imaging Study (IBIS) and Early Autism Risk Longitudinal Investigation (EARLI) are two NIH Autism Center of Excellence Networks that focus on the longitudinal study of high-risk siblings of ASD probands (referred to as high-risk sibs). The principal goal of the IBIS Network is to conduct a longitudinal MRI/DTI and behavioral study of infants at high risk for an autism spectrum disorder (ASD) to explore the association between major brain and behavior changes thought to occur between 6 and 24 months of age. The principal goal of the EARLI Network is to gather data on a high autism risk cohort from conception to age three in order to explore associations between exposures and biomarkers measured during the prenatal and early-postnatal period with autism risk. The IBIS project is collecting data on 544 high risk sibs and 120 typically developing infants over a five year period starting in July 2007. The EARLI project is collecting data on 1200 families over a seven year enrollment period beginning in January of 2009 with a goal of having data through 36 months of age on 1000 high risk siblings. Both projects are funded by the NICHD. The goal of the IBIS/EARLI collaboration will be to expand the scope of each project and allow for expanded study of infants at risk for autism. Autism Speaks funding will allow a 5 year collaboration of both sites, to explore gene/environment interactions in brain development and a pooled molecular genetic analysis of over 1700 siblings. In order to do so, Autism Speaks support ensures that DNA from all family members (both parents and proband) will be collected and that a standardized environmental exposure questionnaire be filled out by all participating mothers at the same time points. Finally, funding will be used to collect enhanced phenotypic data from both studies, ensuring that children are followed up to 36 months of age in both studies. [BSRC]