Observations of the Cosmic Microwave Background (CMB) provide a unique window into the early moments of our universe. Secondary effects on the CMB, such as weak gravitational lensing, further encode information about the subsequent history of our universe. Current ground-based CMB experiments have reached comparable precision on cosmological parameters to the results from the Planck satellite, and future datasets will allow us to further improve upon these measurements. In this talk, I will discuss applications of CMB datasets to detect or constrain Beyond Standard Model (BSM) physics, both alone and in combination with other cosmological probes. CMB data can be used to search for many kinds of new physics, such as light relic particles, asymmetries in neutrino species, and interactions between dark matter and other particles. I will highlight recent results on extended cosmological models from South Pole Telescope (SPT) measurements, and I will discuss the science reach that we expect from upcoming data releases and that we could expect from more futuristic ground-based millimeter-wave telescopes.