To examine bone mass in children and adolescents with autism spectrum disorders (ASD). Risperidone-treated 5 to 17 year-old males underwent anthropometric and bone measurements, using dual-energy X-ray absorptiometry and peripheral quantitative computed tomography. Multivariable linear regression analysis models examined whether skeletal outcomes differed among participants with (n = 30) versus without ASD (n = 156). After adjusting for potential covariates, having ASD was associated with significantly lower trabecular bone mineral density and bone strength at the radius, and with marginally lower total body less head bone mineral content (p < 0.09). No differences at the lumbar spine were observed. ASD are associated with lower bone mass. Future studies should investigate interventions to optimize skeletal health in ASD.