This study was designed to develop effective music therapy strategies to teach mathematical concepts to individuals with Williams Syndrome (WS) by using their affinity and abilities in music as instructional aids. WS is caused by a microdeletion of 16 – 23 genes on chromosome 7q11.23. These missing genes cause common facial appearance, similar physical characteristics, common cognitive and behavioral characteristics, and physiological difficulties, including cardiovascular abnormalities. A well-known trait of people with WS is a pronounced difficulty with mathematics. In addition, individuals with WS are known as music lovers. An “affinity to music” is often used to describe this characteristic. The basic premise for the effectiveness of music therapy intervention for individuals with WS in this study was that, by combining arithmetic with musicing, individuals with WS could be motivated to attend to mathematical tasks and their attention could be held for longer periods, which might enhance their ability to learn and retain the lessons.

A collective case study was the methodological framework for the study. The participants in the study were three individuals diagnosed with WS, ranging 10 to 21 years of age. Sessions took place over a 10-week period, once per week for 40 to 60 minutes, in each participant's home environment. All thirty sessions were digitally recorded and transcribed.

The analysis and interpretation of the sessions identified the participants' roadblocks in their mathematical development in metacognition, visuospatial ability, attention, processing speed, and fine motor skills. The severity of these difficulties was shown to vary among the three participants. While many of the effects of these difficulties overlap and are interrelated, the findings suggest that each difficulty requires a different form of intervention. These findings also suggest that music therapy could offer various strategies that assist in coping with the difficulties. Three primary functions in music were identified as being particularity beneficial for mathematical development: music used to advance cognitive development; music used to encourage and motivate; and music used to provide structure for academic learning interventions.

Based on the findings of the study, several suggestions are made for music therapists working with individuals with WS as well as individuals with other genetic disorders. These suggestions include the importance of specific research on the differences in the roadblocks among the various types of genetic disorders and an informed clinical practice based on knowledge, theory, and research with the particular type of genetic disorder. This study suggests that music therapists might need to develop three sets of music therapy interventions: (1) individuals with WS who do not develop the comprehension of magnitude and cardinality; (2) individuals with WS who develop the basic concepts referred to above, but still struggle with operating numbers such as composition and decomposition; and (3) individuals with WS who develop a basic understanding of numbers and operations and are ready to move on to addition and subtraction. This study demonstrated the strong possibility that music therapy can assist individuals with WS in their mathematical development.