Sandia National Laboratories (SNL), also known as Sandia, is one of three research and development laboratories of the United States Department of Energy's National Nuclear Security Administration (NNSA). Headquartered in Kirtland Air Force Base in Albuquerque, New Mexico, it has a second principal facility next to Lawrence Livermore National Laboratory in Livermore, California, and a test facility in Waimea, Kauaʻi, Hawaii. Sandia is owned by the U.S. federal government but privately managed and operated by National Technology and Engineering Solutions of Sandia, a wholly owned subsidiary of Honeywell International.

Established in 1949, SNL is a "multimission laboratory" with the primary goal of advancing U.S. national security by developing various science-based technologies. Its work spans roughly 70 areas of activity, including nuclear deterrence, arms control, nonproliferation, hazardous waste disposal, and climate change. Sandia hosts a wide variety of research initiatives, including computational biology, physics, materials science, alternative energy, psychology, MEMS, and cognitive science. Most notably, it hosted some of the world's earliest and fastest supercomputers, ASCI Red and ASCI Red Storm, and is currently home to the Z Machine, the largest X-ray generator in the world, which is designed to test materials in conditions of extreme temperature and pressure.

Sandia conducts research through partnership agreements with academic, governmental, and commercial entities; educational opportunities are available through several programs, including the Securing Top Academic Research & Talent at Historically Black Colleges and Universities (START HBCU) Program and the Sandia University Partnerships Network (a collaboration with Purdue University, University of Texas at Austin, Georgia Institute of Technology, University of Illinois Urbana–Champaign, and University of New Mexico).

Sandia National Laboratories' roots go back to World War II and the Manhattan Project. Prior to the United States formally entering the war, the U.S. Army leased land near an Albuquerque, New Mexico airport known as Oxnard Field to service transient Army and U.S. Navy aircraft. In January 1941 construction began on the Albuquerque Army Air Base, leading to establishment of the Bombardier School-Army Advanced Flying School near the end of the year. Soon thereafter it was renamed Kirtland Field, after early Army military pilot Colonel Roy C. Kirtland, and in mid-1942 the Army acquired Oxnard Field. During the war years facilities were expanded further and Kirtland Field served as a major Army Air Forces training installation.

In the many months leading up to successful detonation of the first atomic bomb, the Trinity test, and delivery of the first airborne atomic weapon, Project Alberta, J. Robert Oppenheimer, Director of Los Alamos Laboratory, and his technical advisor, Hartly Rowe, began looking for a new site convenient to Los Alamos for the continuation of weapons development – especially its non-nuclear aspects. They felt a separate division would be best to perform these functions. Kirtland had fulfilled Los Alamos' transportation needs for both the Trinity and Alberta projects, thus, Oxnard Field was transferred from the jurisdiction of the Army Air Corps to the U.S. Army Service Forces Chief of Engineer District, and thereafter, assigned to the Manhattan Engineer District. In July 1945, the forerunner of Sandia Laboratory, known as "Z" Division, was established at Oxnard Field to handle future weapons development, testing, and bomb assembly for the Manhattan Engineer District. The District-directive calling for establishing a secure area and construction of "Z" Division facilities referred to this as "Sandia Base" , after the nearby Sandia Mountains – apparently the first official recognition of the "Sandia" name.

Sandia Laboratory was operated by the University of California until 1949, when President Harry S. Truman asked Western Electric, a subsidiary of American Telephone and Telegraph (AT&T), to assume the operation as an "opportunity to render an exceptional service in the national interest." Sandia Corporation, a wholly owned subsidiary of Western Electric, was formed on October 5, 1949, and, on November 1, 1949, took over management of the Laboratory. The United States Congress designated Sandia Laboratories as a National laboratory in 1979. In October 1993, Sandia National Laboratories (SNL) was managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin. In December 2016, it was announced that National Technology and Engineering Solutions of Sandia, under the direction of Honeywell International, would take over the management of Sandia National Laboratories beginning May 1, 2017; this contract remains in effect as of November 2022, covering government-owned facilities in Albuquerque, New Mexico (SNL/NM); Livermore, California (SNL/CA); Tonopah, Nevada; Shoreview, Minnesota; and Kauaʻi, Hawaii. SNL/NM is the headquarters and the largest laboratory, employing more than 12,000 employees, while SNL/CA is a smaller laboratory, with around 1,700 employees. Tonopah and Kauaʻi are occupied on a "campaign" basis, as test schedules dictate. The lab also managed the DOE/SNL Scaled Wind Farm Technology (SWiFT) Facility in Lubbock, Texas.

Sandia led a project that studied how to decontaminate a subway system in the event of a biological weapons attack (such as anthrax). As of September 2017, the process to decontaminate subways in such an event is "virtually ready to implement," said a lead Sandia engineer.

Sandia's integration with its local community includes a program through the Department of Energy's Tribal Energy program to deliver alternative renewable power to remote Navajo communities, spearheaded by senior engineer Sandra Begay.