Chatham House

The Royal Institute of International Affairs, also known as Chatham House, is a British think tank based in London, England. Its stated mission is "to help governments and societies build a sustainably secure, prosperous, and just world". It is the originator of the Chatham House Rule.

The Royal Institute of International Affairs has its headquarters in central London at 10 St James's Square, which is known as Chatham House. It is a Grade I listed 18th-century building that was designed in part by Henry Flitcroft and was occupied by three British prime ministers, including William Pitt, 1st Earl of Chatham, whose name became associated with the house. Canadian philanthropists Lieutenant-Colonel Reuben Wells Leonard and Kate Rowlands Leonard purchased the property in 1923 and then donated the building to the fledgling institute as its headquarters. As a result, the Chatham House name is used as a metonym for the institute as a whole.

Chatham House accepts individual members, as well as members from corporations, academic institutions, and NGOs.