Experimental cosmologist building and operating CMB telescopes. Directions: (1) South Pole Telescope — PI of SPT series; SPT-3G currently mapping CMB temperature and polarization at arcminute resolution; (2) thermal and kinematic Sunyaev-Zel'dovich effect mapping for galaxy cluster cosmology; (3) CMB gravitational lensing for large-scale structure; (4) CMB-S4 design and planning. Argonne joint appointment. APS and AAAS Fellow.