Background: Abnormalities in the modulation of the glutamate system have been reported by multiple investigators studying animal models, post-mortem brains, and single gene disorders that have overlapping phenotypes with autism. Abnormalities in glutamatergic function have been reported in disorders affecting a variety of behavioral and neurological domains, from mood stability, to cognitive flexibility, memory, and motor function. Numerous studies have reported a variety of memory and motor deficits in children with autism. Whereas the neurobiology of such deficits is an area of active research, there is a paucity of intervention research for such deficits in autism. This study will attempt to study the effect of an NMDA inhibitor, memantine, on memory, and motor praxis/expressive language skills in children with autism. Methods: Children ages 6-12 years who are verbal and meet criteria for Autism Spectrum Disorder will be recruited across 3 sites. After consent, the children will be assessed for memory function, expressive language output and motor skills / praxis. They will then be randomized 1:1 to memantine vs. placebo for 6 months. The effects of this medication on the above mentioned symptoms domains as well as its safety in this population will be studied over the 6 month period.