The 1948 Interzonal tournament held in Saltsjöbaden, Stockholm was a major qualification event for the 1951 World Chess Championship. It was the first Interzonal tournament organised by FIDE, which was at the time emerging as the game's international governing body. Twenty participants competed in a round robin from 16 July to 15 August 1948. The tournament was won by David Bronstein, who along with seven other players advanced to the 1950 Candidates Tournament.
The process of organizing the new World Championship cycle ran into numerous problems in the chaotic post-war environment. In a 1946 meeting in The Hague, FIDE formulated the plan to hold eight Zonal tournaments, with the winners of these events advancing to a new tournament, dubbed the "Interzonal". The top five players from the Interzonal were to advance to the Candidates Tournament alongside the five unsuccessful participants of the upcoming World Championship tournament.
The United States were invited to send two players to the World Championship; it was assumed at the time that Samuel Reshevsky and Reuben Fine, leading grandmasters and participants in the 1938 AVRO tournament, would be chosen. However, there was a feeling within the United States Chess Federation that they should have the right to determine their own selection process, and they decided to send the top two players from the 1946 U.S. Championship. Fine was unable to participate in this event due to his studies, and Reshevsky won the tournament by a 2½ point margin from Isaac Kashdan. It was later decided that Fine would be allowed to play in the World Championship after all, and Kashdan would be treated as the qualifier from the United States Zonal.
The first Zonal event, covering most of Europe, was held in Hilversum, Netherlands in July 1947. The Belgian champion Albéric O'Kelly was the surprise winner, ahead of more fancied players such as Petar Trifunović, Luděk Pachman and László Szabó.
The 1947 Nordic Chess Championship in Helsinki was treated as a Zonal event for World Championship qualification purposes. This event finished in a tie for first place between Eero Böök and Gösta Stoltz. The two played an eight game play-off match, which however also resulted in a tie with one win apiece. Böök was declared the winner due to his superior Sonneborn-Berger score.
The 1947 Canadian championship, won by Daniel Yanofsky, was also treated as a Zonal event, however no other Zonals were organised. Eventually it was decided to hold a ballot among FIDE delegates to determine the make-up of the tournament. From this, a list of sixteen players was created to join O'Kelly, Kashdan, Böök and Yanofsky. In order of selection, the following players were nominated:
In addition an extensive reserve list was created to cater for the inevitable withdrawals:
Players or their federations were required to finance their own travel and accommodation. In the end, O'Kelly, Kashdan, Denker, and Eliskases withdrew. They were replaced by Lilienthal, Stoltz, Lundin and Pirc. Horowitz also declined a place; it is unclear why Pirc was accepted ahead of Ekström, Bernstein and Alexander.
Najdorf was the pre-tournament favourite, however he was in indifferent form; in round 4 he failed to win a won pawn endgame against Kotov, and in round 5 he lost quickly to Lilienthal, who won a brilliancy prize for his effort. Szabó led for most of the tournament but stumbled towards the end. His loss in the final round to tail-ender Lundin allowed Bronstein to overtake him and win the tournament.
|1||David Bronstein (Soviet Union)||x||1||½||1||½||½||½||½||½||½||1||½||½||1||½||1||½||1||1||1||13½|
|2||László Szabó (Hungary)||0||x||½||½||1||½||1||½||½||1||½||1||1||1||½||1||½||½||1||0||12½|
|3||Isaac Boleslavsky (Soviet Union)||½||½||x||½||½||½||0||1||½||1||½||½||1||½||½||½||1||1||1||½||12|
|4||Alexander Kotov (Soviet Union)||0||½||½||x||½||½||½||½||½||½||1||½||½||½||½||1||1||1||1||½||11½|
|5||Andor Lilienthal (Soviet Union)||½||0||½||½||x||1||1||½||½||½||0||½||½||½||1||½||1||½||½||1||11|
|6||Igor Bondarevsky (Soviet Union)||½||½||½||½||0||x||½||½||1||0||½||1||½||0||½||½||1||½||1||1||10½||93.75|
|7||Miguel Najdorf (Argentina)||½||0||1||½||0||½||x||½||½||1||0||1||½||0||½||1||½||½||1||1||10½||93.75|
|8||Gideon Ståhlberg (Sweden)||½||½||0||½||½||½||½||x||½||0||½||1||1||½||½||½||½||1||½||1||10½||93.75|
|9||Salo Flohr (Soviet Union)||½||½||½||½||½||0||½||½||x||½||½||½||½||½||½||½||1||½||1||1||10½||93.25|
|10||Petar Trifunović (Yugoslavia)||½||0||0||½||½||1||0||1||½||x||½||½||0||1||½||½||1||½||1||½||10|
|11||Vasja Pirc (Yugoslavia)||0||½||½||0||1||½||1||½||½||½||x||½||½||0||1||0||½||1||½||½||9½||87.75|
|12||Svetozar Gligorić (Yugoslavia)||½||0||½||½||½||0||0||0||½||½||½||x||1||½||1||1||1||½||0||1||9½||84.50|
|13||Eero Böök (Finland)||½||0||0||½||½||½||½||0||½||1||½||0||x||½||½||½||½||1||1||1||9½||81.25|
|14||Viacheslav Ragozin (Soviet Union)||0||0||½||½||½||1||1||½||½||0||1||½||½||x||0||0||½||0||½||1||8½||78.75|
|15||Daniel Yanofsky (Canada)||½||½||½||½||0||½||½||½||½||½||0||0||½||1||x||0||½||½||½||1||8½||78.25|
|16||Savielly Tartakower (France)||0||0||½||0||½||½||0||½||½||½||1||0||½||1||1||x||0||½||½||½||8|
|17||Ludek Pachman (Czechoslovakia)||½||½||0||0||0||0||½||½||0||0||½||0||½||½||½||1||x||1||½||1||7½|
|18||Gösta Stoltz (Sweden)||0||½||0||0||½||½||½||0||½||½||0||½||0||1||½||½||0||x||½||½||6½|
|19||Lajos Steiner (Australia)||0||0||0||0||½||0||0||½||0||0||½||1||0||½||½||½||½||½||x||½||5½|
|20||Erik Lundin (Sweden)||0||1||½||½||0||0||0||0||0||½||½||0||0||0||0||½||0||½||½||x||4½|
Originally five players were to advance to the Candidates tournament. Following the withdrawal of Reshevsky, Fine and Euwe, this number was increased to eight. The four players who tied for sixth place were to have played off for three spots in the Candidates tournament, but Bondarevsky had to withdraw due to illness, so the other three qualified automatically. According to some accounts, all four players plus Trifunović were originally invited to play in the Candidates Tournament, however following Bondarevsky's withdrawal Trifunović was "uninvited" in order to keep the numbers even.