The Cybersecurity and Infrastructure Security Agency’s (CISA’s) National Risk Management  Center (NRMC) has a dual mission: to analyze and reduce risk to the nation’s critical infrastructure. Following the recommendations of the Cyberspace Solarium Commission, and  a prior Homeland Security Operational Analysis Center (HSOAC) study to explore information technology products and services that could be considered important to protecting  critical infrastructure, the NRMC asked that HSOAC: (1) develop methods advancing CISA’s  concept of risk prioritization through support for the systemically important critical infrastructure (SICI) program initiative;1 (2) advance prior HSOAC work documented in a previous report,2 and accompanying materials, and; (3) aid CISA in responding to congressional  and Executive Office of the President taskers expected during calendar years 2021 and 2022,  and any other relevant changes to CISA requirements. This study was titled “Identifying  Systemically Important Critical Infrastructure,” although concepts evolved, and the sponsor  requested the focus be on identifying and prioritizing systemically important entities.