Controlled studies examining canine therapy in autism spectrum disorder are scarce. This study examined the effectiveness of a "Dog Training Intervention" on adaptive skills, autism severity, and anxiety using a controlled crossover design. Seventy-three participants diagnosed with autism spectrum disorder (M[subscript age] = 4:10 ± 1:0) were divided into two groups that received the dog training intervention during half of the school year in addition to standard-of-care interventions. The dog training intervention, in which the children were taught how to interact with and train dogs, was given twice weekly for 4 months within autism spectrum disorder-specific special education school. Those receiving the dog training intervention first showed significantly increased adaptive social and communication skills compared to the controls, and the gains were maintained after the dog training intervention. Belonging to the first dog training intervention group, higher pre-intervention adaptive skills, higher baseline cognitive ability, and less severe autism severity predicted better adaptive social and communication skills. The controls improved in adaptive skills only during their receipt of dog training intervention after crossover. The positive impact on social communication skills suggests that dog training may serve as an effective model for establishing social interaction. Dog training intervention appears to be an effective adjunct treatment to interventions provided in special education schools for children with autism spectrum disorder.