The Cavendish Laboratory is the Department of Physics of the University of Cambridge. The Department is itself part of the School of Physical Sciences. It was built in 1873 as a teaching laboratory. It was initially on the New Museums site off Free School Lane, in the centre of Cambridge. After perennial space problems, it moved to Madingley Road 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 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 Watson came from the U.S.A. and they together discovered the DNA double helix. For their work while in the Cavendish Laboratory they were awarded the Nobel Prize in Physiology or Medicine for 1962.

There is a Cavendish Professorship of Physics.