GABA, the mature brain’s primary inhibitory neurotransmitter, has been proposed to contribute to the development of Autism Spectrum Disorder (ASD) and the maintenance of ASD symptoms. Investigations have found reductions in GABA in children and adolescents with ASD. In the current study, GABA levels were measured using GABA-edited MEGA-PRESS in the left parietal lobe. The study compared 24 children with ASD and 35 typically developing (TD), aged 4-12 years. Increasing GABA concentration with age was found in the ASD participants but not in the TD cohort, suggesting a distinct pattern of GABA development in ASD within the parietal lobe.