The stereotypic behavior of children (N = 26) while in a playroom session with their parent was studied. The sample included children with a pervasive developmental disorder, an attention-deficit/hyperactivity disorder, a developmental expressive language disorder, or a developmental receptive language disorder and normally developing children. Stereotypic behaviors associated with distress, elation, and composure were compared on mean duration and form of the stereotypies and heart rate changes around the onset of the stereotypies. Results showed that stereotypies associated with different moods differed in all variables studied. Results confirm that a valid classification scheme for stereotypic behaviors is needed as they indicate different functions of individual stereotypies.