Dysregulation of activity linked with development was analysed in 12 children with intellectual disabilities (ID) and in 12 children with autism (ASD) matched on their developmental age (18 months). The "Batterie d'Evaluation du Developpement Cognitif et Social" [Adrien, J. L. (1996). "Autisme du jeune enfant. Developpement psychologique et regulation de l'activite" ["Autism in the young child: Psychological development and behavioral regulation"]. Paris: Expansion Scientifique Francaise] and the [left angle quote]Regulation Disorders Evaluation Grid[right angle quote] [Adrien, J. L., Rossignol-Deletang, N., Martineau, J., Couturier, G., & Barthelemy, C. (2001). Regulation on cognitive activity and early communication development in young autistic, mentally retarded, and young normal children. "Developmental Psychobiology," 39(2), 124-136] were used. T-test comparisons, partial correlation controlling for chronological age and clusters analyses by cases were completed. Children with ASD showed more dysregulation than ID children and both groups showed different patterns of specific dysregulation disorders. Dysregulation of activity was linked to development but correlations were much more numerous and intense within ASD group compared to ID group.