This grant provides operational and administrative support to the governing secretariat of the Deep Carbon Observatory (DCO), headquartered at the Carnegie Institution for Science, which is charged with coordinating and synthesizing the work of DCO’s researchers, who number more than 1,300 and are spread across some 40 countries worldwide. Grant funds will offset operational costs of the international steering committee; provide support for the secretariat chairs, geoscientists Robert Hazen and Craig Manning; facilitate the DCO’s grand finale in Washington, D.C. in October 2019; and support several activities aimed at securing the legacies of the DCO at the conclusion of Foundation funding.