This bachelor thesis concerns an analysis of the concept of lyric improvisation, meaning improvising over the melody and lyrics of a jazz standard within the classic vocal jazz tradition. In order to explore this concept, I have studied the use of melody alteration in the song “Mean to Me” as performed by the renowned jazz vocalists; Sarah Vaughan, Betty Carter, and Ella Fitzgerald. After transcribing one chorus each from the three singers, where they improvised melodically and rhythmically while maintaining the lyric, I discovered specific vocal improvisational tools they all used, which I then formulated into a list. The list divided the tools into three categories; melodic, rhythmic, and lyric-related tools. Then I practiced applying these tools to my craft as a jazz vocalist and later presented my adaption of the concept of lyric improvisation in a concert at the Royal College of Music in Stockholm. In conclusion, studying vocal tools for lyrical improvisation made me discover that it’s not merely the selection of tools but how one uses and combines the tools that define a jazz vocalist’s individualistic, improvisational style.