There is an ongoing need for clinical accountability related to evaluating the effectiveness of music therapy interventions for children with autism spectrum disorder. Moreover, quantifying outcomes of client-centered approaches, such as music-centered music therapy when working with individuals with ASD, has consistently shown to be challenging. Goal attainment scaling (GAS) provides an established practice-based method for quantitatively evaluating individualized treatment goals. Although GAS has been used by a variety of disciplines, it has yet to be utilized in the field of music therapy. The purpose of this paper was to describe and illustrate the use of GAS as a method of evaluating progress toward developmentally based music-centered music therapy goals for children with autism spectrum disorder.