To compare the efficacy of one-on-one versus group-based aquatic therapy on the social interactions, behaviors and physical activities of children with autism spectrum disorders (ASDs).

Eligibility criteria:

• DSM-V diagnosis of Autism Spectrum Disorder or DSM-IV diagnosis of Asperger's syndrome or high functioning atypical autism or pervasive development disorder - not otherwise specified or else the typical clinical findings and suspicion of an ASD
• Treatment naïve to prior aquatic therapy

Exclusion criteria:

• Not willing to undergo an investigational treatment
• Unable to cooperate well enough to safely participate in aquatic therapy under the protocol guidelines
• Known allergies to pool chemicals
• Other significant co-morbidities which may include (but is not limited to): severe cerebral palsy with low motor function, advanced pulmonary disease, home oxygen requirement, spina bifida with low motor function, permanent feeding tubes, poorly controlled seizure disorder, chronic indwelling urinary catheters or any condition causing severe cognitive impairment