The Atmospheric Characterization Working Group (ACWG) for NASA’s TESS mission was initially envisioned to conduct pre-launch activities for maximizing TESS’s impact on exoplanet atmosphere studies. Now that TESS has completed its prime mission and entered its extended mission phase, the ACWG has shifted its focus. Currently and going forward, the role of the ACWG is to ensure the successful legacy of the TESS mission, specifically as it relates to the atmospheric characterization of its discovered exoplanets. In this context, success means pursuing a goal that the TESS-discovered exoplanets be observed by an optimal set of ground-based and spaced-based facilities in a coordinated manner, so as to extract population-level and individual planets’ atmospheric properties. In this talk I will introduce the activities that the TESS ACWG has been undertaking to support its main goals. I will review criteria for joining the ACWG, and I will present the many ways in which the ACWG is working to support the atmospheric characterization community as it endeavors to further our understanding of the multitude of TESS-discovered exoplanets.