Executive Summary This article provides detailed estimates of foreign-born (immigrant) workers in the United States who are employed in “essential critical infrastructure” sectors, as defined by the Cybersecurity and Infrastructure Security Agency (CISA) of the US Department of Homeland Security (DHS) (DHS 2020). Building on earlier work by the Center for Migration Studies (CMS), the article offers exhaustive estimates on essential workers on a national level, by state, for large metropolitan statistical areas (MSAs), and for smaller communities that heavily rely on immigrant labor. It also reports on these workers by job sector; immigration status; eligibility for tax rebates under the Coronavirus Aid, Relief, and Economic Security Act (CARES Act); and other characteristics. It finds that: Sixty-nine percent of all immigrants in the US labor force and 74 percent of undocumented workers are essential workers, compared to 65 percent of the native-born labor force. Seventy percent of refugees and 78 percent of Black refugees are essential workers. In all but eight US states, the foreign-born share of the essential workforce equals or exceeds that of all foreign-born workers, indicating that immigrant essential workers are disproportionately represented in the labor force. The percentage of undocumented essential workers exceeds that of native-born essential workers by nine percentage points in the 15 states with the largest labor force. In the ten largest MSAs, the percentages of undocumented and naturalized essential workers exceed the percentage of native-born essential workers by 12 and 6 percent, respectively. A total of 6.2 million essential workers are not eligible for relief payments under the CARES Act, as well as large numbers of their 3.8 million US citizen children (younger than age 17), including 1.2 million US citizen children living in households below the poverty level. The foreign-born comprise 33 percent of health care workers in New York State, 32 percent in California, 31 percent in New Jersey, 28 percent in Florida, 25 percent in Nevada and Maryland, 24 percent in Hawaii, 23 percent in Massachusetts, and 19 percent in Texas. Section I of the article describes the central policy paradox for foreign-born workers during the COVID-19 pandemic: that they are “essential” at very high rates, but many lack status and they have been marginalized by US immigration and COVID-19-related policies. Section II sets forth the article’s main findings. Section III outlines major policy recommendations.