UPDATE: DSM-5 (2013) introduced several changes which are crucial to note here:  Diagnoses that were under the pervasive developmental disorders category were merged into autism spectrum disorder (ASD). Two diagnoses--childhood disintegrative disorder and Rett syndrome--were removed.

Here's the CDC's ASD page--study this, not the now-outdated PDDs!

Original post:

Exam prep wiki of the day.  The PDDs are:

Pervasive developmental disorder details at Wikipedia.

March 19, 2009