The 91 institutions with CMB-S4 team members span 15 countries and 21 US states.
US Institutions
| Argonne National Laboratory |
| Arizona State University |
| Berkeley Center for Cosmological Physics |
| Brookhaven National Laboratory |
| Brown University |
| California Institute of Technology |
| Case Western Reserve University |
| Center for Astrophysics | Harvard & Smithsonian |
| Columbia University |
| Cornell University |
| Dartmouth College |
| Fermi National Accelerator Laboratory |
| Flatiron Institute |
| Florida State University |
| Harvard University |
| Haverford College |
| Institute for Advanced Study |
| Johns Hopkins University |
| Jet Propulsion Laboratory |
| Kavli Institute for Cosmological Physics |
| Kavli Institute for Particle Astrophysics and Cosmology |
| Lawrence Berkeley National Laboratory |
| Michigan State University |
| NASA Goddard Space Flight Center |
| National Institute of Standards and Technology |
| Pennsylvania State University |
| Princeton University |
| Rice University |
| SLAC National Accelerator Laboratory |
| Southern Methodist University |
| Stanford University |
| Stony Brook University |
| Syracuse University |
| UC Berkeley |
| UC Davis |
| UC Irvine |
| UC Los Angeles |
| UC San Diego |
| UC Santa Barbara |
| University of Chicago |
| University of Cincinnati |
| University of Colorado Boulder |
| University of Illinois at Urbana-Champaign |
| University of Michigan |
| University of Minnesota |
| University of New Mexico |
| University of Pennsylvania |
| University of Pittsburgh |
| University of Southern California |
| University of Virginia |
| University of Wisconsin Madison |
| Washington University St. Louis |
| Yale University |
International Partners
| Aalto University | Finland |
| Associated Universities Incorporated | Chile |
| AstroParticle & Cosmology Laboratory | France |
| Axe Marseille | France |
| Ben Gurion University | Israel |
| Cardiff University | UK |
| CEA Saclay | France |
| Canadian Institute for Theoretical Astrophysics | Canada |
| European Southern Observatory | Germany |
| ICJLab | France |
| INFN | Italy |
| Institut d’Astrophysique de Paris | France |
| Kavli Institute for the Physics and Mathematics of the Universe | Japan |
| KEK | Japan |
| Kyoto University | Japan |
| LMU Munich | Germany |
| McGill University | Canada |
| National Taiwan University | Taiwan |
| Oxford University | UK |
| Perimeter Institue | Canada |
| Pontificia Universidad Católica de Chile | Chile |
| Simon Fraser University | Canada |
| SISSA | Italy |
| Stockholm University | Sweden |
| Universita degli Studi di Milan | Italy |
| University of British Columbia | Canada |
| University of Cambridge | UK |
| University of Geneva | Switzerland |
| University of Groningen | Netherlands |
| University of Manchester | UK |
| University of Melbourne | Australia |
| University of Milano-Bicocca | Italy |
| University of Sussex | UK |
| University of Tokyo | Japan |
| University of Toronto | Canada |