The diagnostic category pervasive developmental disorders (PDD), as opposed to specific developmental disorders (SDD), refers to a group of five disorders characterized by delays in the development of multiple basic functions including socialization and communication. The most commonly known PDD is (1) Autism, with the remaining identified as (2) Rett syndrome, (3) Childhood disintegrative disorder, (4) Asperger syndrome, and (5) Pervasive Developmental Disorder Not Otherwise Specified (or PDD-NOS). National Dissemination Center for Children with Disabilities (NICHCY) (October 2003) blank">Disability Info: Pervasive Developmental Disorders (FS20). Fact Sheet 20 (FS20)

Parents may note symptoms of PDD as early as infancy and typically onset is prior to 3 years of age. PDD itself generally does not affect life expectancy. However, PDDs are correlated with poverty, suicides, crimes, and a variety of medical problems.

There is a division among doctors on the use of the term PDD. Many use the term PDD as a short way of saying _PDDNOS. Others use the general category label of PDD because they are hesitant to diagnose very young children with a specific type of PDD, such as autism. Both approaches contribute to confusion about the term, because the term PDD actually refers to a category of disorders and is not a diagnostic label.