The Cavendish Laboratory is Cambridge University's Department of Physics, and is part of the university's School of Physical Sciences. It was built in 1873 as a teaching laboratory. It was initially on the New Museums Site in the centre of Cambridge but, after perennial space problems, it moved to its present site in West Cambridge in the early 1970s.

The Department is named after Henry Cavendish, a famous physicist, and a member of the Dukes of Devonshire branch of the Cavendish family. Another family member, William Cavendish, 7th Duke of Devonshire, was Chancellor of the University, and he gave money to endow the laboratory in memory of his learned relative.

So far, 28 Cavendish researchers have won Nobel Prizes.

The Cavendish Laboratory has had an important influence on biology, mainly through the application of X-ray crystallography to the study of structures of biological molecules. Francis Crick already worked in the Medical Research Council Unit, headed by Max Perutz and housed in the Cavendish Laboratory, when James Watson came from the United States and they made a breakthrough in discovering the structure of DNA. For their work while in the Cavendish Laboratory, they were awarded the Nobel Prize in Physiology or Medicine for 1962.

Other areas in which the Laboratory has been very influential since 1950 include:-

• Superconductivity (under A Brian Pippard );
• High Voltage Electron Microscopy;
• Radio Astronomy (under Martin Ryle and Antony Hewish), with the Radio Astronomy Group's telescopes being based at Mullard Radio Astronomy Observatory

The current head of the Cavendish (called the 'Jacksonian Professor of Natural Philosophy') is Malcolm Longair. There is also a Cavendish Professorship of Physics position.