Characterization of academic functioning in children with autism spectrum disorder (ASD), particularly predictors of achievement, may have important implications for intervention. The current study aimed to characterize achievement profiles, confirm associations between academic ability and concurrent intellectual and social skills, and explore preschool predictors of school-age academic achievement in a sample of children with ASD. Children with ASD (n = 26) were evaluated at the approximate ages of two, four, and ten. Multiple regression was used to predict school-age academic achievement in reading and mathematics from both concurrent (i.e. school-age) and preschool variables. Children with ASD demonstrated a weakness in reading comprehension relative to word reading. There was a smaller difference between mathematics skills; math reasoning was lower than numerical operations, but this did not quite reach trend level significance. Concurrent IQ and social skills were associated with school-age academic achievement across domains. Preschool verbal abilities significantly predicted school-age reading comprehension, above and beyond concurrent IQ, and early motor functioning predicted later math skills. Specific developmental features of early ASD predict specific aspects of school-age achievement. Early intervention targeting language and motor skills may improve later achievement in this population.