How can I tell if a child has autism?

No two children with autism are alike, but there are some signs that many of them share and that experts agree may be as recognizable as early as the toddler years, or even sooner. Children on the spectrum generally have difficulty relating to others; they may hardly speak, and if they do, they may not communicate in ways that other people can easily understand (they may screech loudly when they're upset, for example, instead of crying). They don't usually sustain eye contact – it's too intense -- and have trouble reading social cues. They're also prone to repetitive behaviors, flapping their hands constantly or uttering the same phrase over and over again. They may also be more sensitive than typically developing children, or dramatically less so, to sights, sounds and touch.