Abstract Sandia National Laboratories, located in Albuquerque, New Mexico, was originally a part of Los Alamos Laboratory. In 1949, AT&T agreed to manage Sandia, which they did for the next 44 years. During those Cold War years, Sandia was the prime weapons engineering laboratory for Los Alamos and Lawrence Livermore. As such, it bore prime responsibility for designing and adapting nuclear weapons for the military services’ delivery systems, and ensuring the safety and reliability of the stockpile. The Labs’ history has been unevenly documented, hindered by the secret nature of its work and the desire of management to maintain a low public profile. There have been three history programs at Sandia: a restricted history published internally in 1963; another history program in the early 1980s that resulted in a history of the Labs’ first decade; and the current history program dating from the mid-1990s, which has published a general history and several monographs. This article discusses the challenges and problems inherent in documenting the history of a national weapons laboratory during the last 50 years.