There appears to be no single cause of autism. Many factors come into play and there is much research to be done. New research is providing important clues. It is widely accepted that genetic predisposition combined with environmental factors (exposure to pollutants, pesticides and chemicals) play a key role. For more information on this topic, visit the FAQ section of the CDC website at http://www.cdc.gov/ncbddd/autism/index.html (Select “Related Topics”)