Red supergiant stars (RSGs) are an end stage of massive star evolution. Among the notable behaviors of stars during this stage are their irregular and semi-regular variability and mass-loss. In order to better understand the sources of these phenomena, we collected high resolution optical interferometric observations of 17 RSGs using the Center for High Angular Resolution Astronomy (CHARA) Array at Mount Wilson between 2015 and 2016. Here, we present stellar diameters derived from these data. We comment on evidence of surface asymmetries on those stars for which we were able to obtain closure phases and present an example image for one of these objects. In addition, we have obtained near-contemporaneous spectroscopy of these stars using SpeX on the NASA InfraRed Telescope Facility (IRTF). We have developed libraries of synthetic spectra derived from spherical MARCS, PHOENIX, and SATLAS stellar atmospheres, and are currently working to derive fundamental stellar parameters with these data.

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