Individuals with autism spectrum disorder (ASD) can experience difficulties functioning in society due to social communication deficits and restrictive and repetitive behaviors. Music therapy has been suggested as a potential intervention used to improve these deficits in ASD. The current systematic literature review focuses on two methods of music therapy: improvisational music therapy (IMT) and singing/listening to songs. We review the extant literature and the associated methodological limitations, and we propose a framework to assess the effectiveness of music therapy as an intervention in ASD. We suggest the creation of a standardized framework that should utilize neuroimaging tools as an objective marker of changes induced by music therapy as well as a combination of functional and behaviourial outputs, rather than assessment methods addressing a broad range of functional and behavioural outputs, rather than only the main symptoms. The methodological limitations found in the current literature prevent us from making a strong statement about the effects of music therapy in autism. We consider treatment fidelity assessments as the key to successful future attempts to truly understand music therapy effects in ASD.