Asperger's syndrome (or disorder) is a developmental disorder in which people have severe difficulties understanding how to interact socially. People with Asperger's syndrome may not recognize verbal and nonverbal cues or understand normal social rules, such as taking turns talking or recognizing personal space.

Asperger's syndrome and autism belong to a class of disorders called pervasive developmental disorders. Asperger's syndrome shares some similarities with autism. Like those with autism, children with Asperger's syndrome have abnormal social interactions, facial expressions, and gestures, and unusually focused interests. Unlike those with autism, children with Asperger's syndrome usually have normal intelligence and language development (although the rhythm, pitch, and emphasis are irregular), age-appropriate self-reliance, and interest in the world around them.

Children with Asperger's syndrome have a better outlook than those with other developmental disorders. Many lead productive, independent lives in adulthood.

Asperger's syndrome affects males more than females. Its cause is unknown, although it tends to run in families, suggesting a possible genetic link.