Section 105 of the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) of 1980, as amended by the Superfund Amendments and Reauthorization Act (SARA) of 1986, requires the US Environmental Protection Agency (EPA) to maintain a National Priorities List (NPL) of releases or potential releases of hazardous substances, pollutants, or contaminants that warrant further investigation to determine if they pose risks to human health and the environment. Typically a site is placed on the NPL based on its score derived by applying the Hazard Ranking System (HRS), a screening mechanism EPA uses to evaluate the relative threat to human health and the environment posed by the release, or potential release, of hazardous substances into the environment. Sites scoring 28.50 or greater are eligible for the NPL. Additionally, each state may designate one top-priority site, regardless of the HRS score. Infrequently, EPA may utilize provisions established under 40 CFR 300.425(c)(3) to place a site on the NPL. A site may be deleted from the NPL if it is determined that no further response is required to protect human health and the environment. To date, EPA has deleted 51 sites from the NPL. The criteria and procedures for deleting a site from the NPL, as established by the National Oil and Hazardous Substances Pollution Contingency Plan, otherwise known as the National Contingency Plan (NCP), and other relevant policies are the subject of this Information Brief.