Social communication and self-esteem are often affected in adults with autism spectrum disorder. Implementation and evaluation of interventions targeting social skills are challenged due to specific characteristics of autism. Intensive, valid evaluation of social skills programs is needed. In this explorative multiple case study, we examined effects and working mechanisms of dog-assisted therapy on social communication and self-esteem, by analyzing detailed observations with Monte Carlo permutation tests (testing against 10,000 random samples) and using self- and other-reports in N=6 high-functioning adults with ASD. Results showed significant positive effects on secure body posture. There was an indication of improved self-esteem and more spontaneous touching of the dog, while no convincing increase was found for verbal initiatives. Cross-correlation analyses revealed that touching the therapy dog may be an important determinant to elicit social development in Animal Assisted Therapy (AAT). Considering preliminary results, we recommend exploring underlying mechanisms more thoroughly with real-time observations, accounting for possible gender-effects.