PDD-NOS 

(Pervasive Developmental Disorder -- Not Otherwise Specified)

PDD-NOS is any one of a group of conditions that interfere with social development, communication and thinking skills.  Although some people who have PDD have mental retardation, others have normal IQs.  Autism and Asperger Syndrome are two well-known types of PDD.  Sometimes, when children have some, but not all, of the signs of a disorder such as autism or Asperger Syndrome, they are said to have PDD.