洛斯阿拉莫斯国家实验室 Los Alamos National Laboratory，LANL  
洛斯阿拉莫斯国家实验室（Los Alamos National Laboratory，LANL，曾被称为洛斯阿拉莫斯实验室、洛斯阿拉莫斯科学实验室），隶属美国能源部的国家实验室，位于新墨西哥州的洛斯阿拉莫斯 (新墨西哥州)。
1945年7月，该实验室研制首枚原子弹，曼哈顿计划的所在地，在冷战时扮演美国军事研究的重要基地。实验室目前是全球最大的跨学科研究机构之一。它是新墨西哥州北部最大的研究机构和雇员最多的机构，约有10,400名加利福尼亚大学雇员，以及大约2,800名合同雇员。
实验室约三分之一的技术人员是物理学专家、四分之一是工程师、六分之一是化学和材料专家，其余的工作在数学和计算科学、生物科学、地质科学等其他学科。也有外部的专家和学生来实验室做访问研究工作。实验室联合大学和工业界进行能源方面的基础和应用研究。实验室年度预算约为22亿美元。
洛斯阿拉莫斯是美国设计核武器的两个机构之一，另一个是劳伦斯利福摩尔国家实验室（始于1952年）。
不过，该实验室近年出现多宗丑闻，包括遗失机密数据、错误起诉一名华人科学家李文和充当间谍，2004年实验室需要大规模重组，2006年6月，多年来一直营运实验室的加州大学交出管理权，实验室交由新成立的“洛斯阿拉莫斯国家安全委员会”全面接手，成员包括加州大学及多间军火营办商，新委员会的目标将要令实验室盈利。

Los Alamos National Laboratory (or LANL; previously known at various times as Project Y, Los Alamos Laboratory, and Los Alamos Scientific Laboratory) is one of two laboratories in the United States where classified work towards the design of nuclear weapons is undertaken. The other, since 1952, is Lawrence Livermore National Laboratory. LANL is a United States Department of Energy (DOE) national laboratory, managed and operated by Los Alamos National Security (LANS), located in Los Alamos, New Mexico. The laboratory is one of the largest science and technology institutions in the world. It conducts multidisciplinary research in fields such as national security, space exploration, renewable energy,[2] medicine, nanotechnology, and supercomputing.
LANL is the largest institution and the largest employer in northern New Mexico, with approximately 9,000 direct employees and around 650 contractor personnel.[3] Additionally, there are roughly 120 DOE employees stationed at the laboratory to provide federal oversight of LANL's work and operations. Approximately one-third of the laboratory's technical staff members are physicists, one quarter are engineers, one-sixth are chemists and materials scientists, and the remainder work in mathematics and computational science, biology, geoscience, and other disciplines. Professional scientists and students also come to Los Alamos as visitors to participate in scientific projects. The staff collaborates with universities and industry in both basic and applied research to develop resources for the future. The annual budget is approximately US$2.2 billion.