Pervasive developmental disorder not otherwise specified (PDD-NOS) is a historic psychiatric diagnosis first defined in 1980 that has since been incorporated into autism spectrum disorder in the DSM-5 (2013).

According to the earlier DSM-IV, PDD-NOS referred to "mild or severe pervasive deficits in the development of reciprocal social interaction and/or verbal and nonverbal communication skills, or when stereotyped behavior, interests,