Spectroscopic and electronic field-effect transistor measurements reveal complimentary information about molecular interactions with single-walled carbon nanotubes (SWNTs). Here we demonstrate how these two complimentary techniques can be combined to further understand electronic modifications of the SWNTs. The complimentary nature of these techniques stems from the perturbation of the electronic structure of SWNTs upon electronic interaction with an electron-donating, or -accepting species.