Vieregg's research also focuses on mapping the cosmic microwave background, or CMB, the relic light from the early moments of the universe, to illuminate the universe's early history. She is involved with the South-Pole based Keck Array and BICEP3 experiments, which measure CMB polarization. She is the technical coordinator and an executive member of CMB-S4, which will use 21 telescopes at the South Pole and the Chilean Atacama Cosmology Telescope to survey the microwave sky.