Outcomes-oriented studies and lyric analyses have been extensively used to understand the effects of therapeutic songwriting. There is a notable absence of investigations that focus on the role of the music and the music creation process within the therapeutic songwriting process. This study contributes to this gap by investigating 45 music therapists’ perceptions of the role of music in the therapeutic songwriting process. Modified grounded theory methods led to the construction of three themes with 18 subthemes: 1) music conveys messages and emotions, 2) music has clinical purpose, and 3) music enhances self-expression. A key outcome of the findings is that analysing music alongside the lyrics ensures that the song’s meaning and the inner world of the songwriter are accurately interpreted.