Music Therapy can be broadly described as the use of Music in a therapeutic context in order to help improve mental health. Music Therapy does not simply imply the playing of music to patients, relaxing though this may be, but in fact it does involve more active involvement of the patient, so as to use the power of music in order to help improve the mental health of patients and in order to treat mental health conditions. We review the evidence for the effect of Music Therapy on Depression, Anxiety, Schizophrenia, Sleep Disorders, and Dementia. Encouraging singing appears to be a good adjunct to treating all of these conditions, and it also seems to help bonding between mothers and children within families. Music appears to be beneficial to both the individual, and also to the improvement of social cohesion. The reasons for this must reside in the nature of music itself as an art form which supports human interactions within society.