For hundreds of years, it has been observed that people with aphasia can sing words fluently, even though they cannot speak. This thesis will investigate how this observation has led to therapy methods, the goals of which are to facilitate propositional speech using music, and how and why these show good results. Various kinds of literature relating to this area will be presented, as well as interviews with music therapists having experience with aphasic patients, an interview with a former aphasic patient who was a musician prior to the impairment and who used music during rehabilitation, as well as an observation by a music therapy group session on clients with speech impairments. The findings are that music therapeutic methods seem to yield good results, and observations, vocal output measurements as well as brain imaging show changes following therapy. Which are the mechanisms that music provides that facilitate the changes are being debated, and there is no formal agreement about this at this juncture; there is, for instance, debate whether the left or the right hemisphere takes over the processing of language. Music does motivate rehabilitation and reduce mood impairments, if applied properly. Aspects of music therapy—other than music itself—may also be important for the positive outcomes, such as the tradition of the therapy in contrast with other therapies, since music therapy is more method-oriented than problem-oriented, and depends on the intensity of the therapy that is suggested.