Each subject's participation in the study will consist of three visits: a screening visit and two identical study visits 1-3 weeks apart. Each visit will last for approximately 2 hours. During the first study visit the participants will provide informed consent. patients will then receive a thorough medical history and neurological and physical exam by a licensed physician with training in pediatric medicine. This will evaluate for underlying neurological disorders that would be exclusionary (e.g. motor impairments, epilepsy, medication contraindications etc.) All subjects will also complete a neuropsychological evaluation including IQ and ASD specific evaluations. If eligible to continue, the participant will then return within two weeks to undergo the first TMS evaluation. The TMS procedure will then be repeated 1-3 weeks later. The two identical TMS study visits aim to address reliability of the TMS-based measures: Investigators hypothesize that the TMS measures will be consistent across sessions within all study groups (ASD and controls, adults and children, low- and high-functioning individuals). Such test-retest reliability data are critical to explore the utility of the TMS measures as a potential marker for diagnosis and therapeutic efficacy of an intervention. Investigators thus anticipate that data from the proposed studies will address an important need for a rapid, noninvasive, reliable and safe endophenotype available to patients with ASD across ages and level of function.