Chatham House, also known as the Royal Institute of International Affairs, is a London think tank. It is a non-profit, non-governmental organization. It analyses and promote the understanding of major international issues and current affairs.
Chatham House is one of the world's leading organizations in this area. It takes its name from its premises, a Grade I listed 18th-century house in St. James's Square, once occupied by three British prime ministers, including William Pitt, 1st Earl of Chatham.
In a recent report, Chatham House is ranked the second most influential think tank in the world after the Brookings Institution, and the world's most influential non-US think tank. In 2009, Chatham House was also named the top non-US think tank by Foreign Policy magazine.
Chatham House has had distinguished presidents from each of the three main political parties at Westminster: Sir John Major, former UK Prime Minister, Lord Ashdown (1941-2018), former EU Special Representative in Bosnia and Herzegovina and former leader of the Liberal Democrats, and Baroness Scotland, the former Attorney General.