Precise control of the vocal tract configuration is of critical importance for producing the desired acoustic characteristics of singing. The pattern of acoustic resonances generated by a given vocal tract shape influences vowel identity, voice quality (timbre), and, to some degree, the spectral characteristics of the voice excitation source itself. This chapter is broadly focused on how the vocal tract shape can be tuned (i.e., modified) in subtle ways to enhance the signal radiated from a singer to an audience. In particular, the vocal tract shape contributions to the “singing formant,” the enhancement of vibrato, and harmonic/formant alignment are discussed.