The International Tennis Federation, abbreviated as ITF, is the governing body of world tennis, wheelchair tennis, and beach tennis. It was founded in 1913 as the International Lawn Tennis Federation by twelve national tennis associations. As of 2016,^[update] there are 211 national and six regional associations that make up the ITF's membership. In 2026 it will be renamed as World Tennis.

The ITF's governance responsibilities include maintaining and enforcing the rules of tennis, regulating international team competitions, promoting the game, and preserving the sport's integrity via anti-doping and anti-corruption programs. The ITF partners with the Association of Tennis Professionals (ATP) and the Women's Tennis Association (WTA) to govern professional tennis.

The ITF organizes annual team competitions for men (Davis Cup), women (Billie Jean King Cup), and mixed teams (Hopman Cup), as well as tennis and wheelchair tennis events at the Summer Olympic and Paralympic Games on behalf of the International Olympic Committee. The ITF sanctions circuits that span age ranges (junior, professional men and women, and non-professional players aged 30 and above) as well as disciplines (wheelchair tennis; beach tennis). In addition to these circuits, the ITF also maintains rankings for juniors, non-professional adults (Masters tour), wheelchair and beach tennis.

Duane Williams, an American who lived in Switzerland, is generally recognized as the initiator and driving force behind the foundation of the International Tennis Federation. He died in the sinking of the RMS Titanic. Originally called the International Lawn Tennis Federation (ILTF) it held its inaugural conference at the headquarters of the Union des Sociétés Françaises de Sports Athlétiques (USFSA), in Paris, France on 1 March 1913 which was attended by 12 national associations. Three other countries could not attend but had requested to become a member. The 15 founding countries were: Australasia (Australia and New Zealand), Austria, Belgium, Denmark, France, Germany, Great Britain, Hungary, Italy, Netherlands, Russia, South Africa, Spain, Sweden, and Switzerland. Canada, Norway, and the United States were also invited but declined to join. Voting rights were divided based on the perceived importance of the individual countries, with Great Britain's Lawn Tennis Association (LTA) receiving the maximum six votes.

The LTA was given the perpetual right to organize the World Grass Championships, which led to a refusal by the United States Lawn Tennis Association (USLTA) to join the ILTF as they were of the opinion that this title should be given to the Davis Cup. France received permission to stage the World Hard Court Championships until 1916 and additionally a World Covered Court Championships was founded. The USLTA joined in 1923 on the basis of two compromises: the title 'World Championships' would be abolished, and wording would be 'for ever in the English language'. The World Championships were replaced by a new category of Official Championships for the main tournaments in Australia, France, England, and the United States; now known as the four Majors or Grand Slam events. In 1924, the ILTF became the officially recognised organisation with authority to control lawn tennis throughout the world, with official ILTF Rules of Tennis.

In 1939 the ILTF had 59 member nations. Its funds were moved to London, England during World War II and from that time onward the ITF has been run from there. It was based at Wimbledon until 1987, when it moved to Barons Court, next door to Queen's Club. It then moved again in 1998 to the Bank of England Sports Ground, Roehampton, its current base of operations. In 1977 the word 'Lawn' was dropped from the name of the organization, in recognition of the fact that most tennis events were no longer played on grass.

In reaction to the 2022 Russian invasion of Ukraine, the ITF cancelled all events in Russia and Belarus. The ITF also excluded Russia from international team events, which include the Davis Cup, the Billie Jean King Cup, and the ATP Cup, and suspended the Russian Tennis Federation. However, the ATP and the WTA refused to yield to international pressure to ban individual players from competition. Russian players will carry on, but not play under the Russian national flag.

Its official annual is The ITF Year, describing the activities of the ITF over the last 12 months. This replaced World of Tennis, which was the ITF official annual from 1981 through 2001. In addition, it publishes an official magazine three times a year.