The April 20, 2010, oil spill that followed the explosion of the Mobile Offshore Drilling Unit, Deepwater Horizon, was the largest in United States history. This spill was also the first Spill of National Significance—a spill so complex that it required extraordinary coordination of Federal, State, local, and responsible party resources to contain and clean up the discharge. As the lead Federal agency for oil spill or hazardous material incidents in United States coastal waters, the United States Coast Guard (USCG) served as the Federal On-Scene Coordinator for response to this oil spill. Seven after action reports containing 549 recommendations were issued in the wake of this incident. Our objective was to determine whether the USCG’s oversight of recommendations made in Deepwater Horizon oil spill after action reports was effective for tracking corrective actions.