Isaac Yefremovich Boleslavsky was born in Zolotonosha, Ukraine on June 9, 1919. His family later moved to Dnepropetrovsk, where Isaac learned chess at the age of 9 in 1928 at the House of Pioneers.
In 1936 he took 3rd place in the USSR Junior Championship, held in Leningrad.
In 1938 he won the Ukraine championship at the age of 19.
In 1939 he again won the Ukraine championship and qualified to play in the USSR championship at the age of 20. He gained his chess master title in 1939.
In 1940 he played in the 12th USSR championship in Moscow. He won 8 of his last 10 games and tied for 5th-6th. At the end of 1940 he won the Ukraine championship for the 3rd time in a row.
In 1941 he participated in the match-tournament for the title of Absolute Champion of the USSR and took 4th place. He defeated Keres and Lilienthal in matches. When World War II broke out, he did not have to serve in the Army because of weak eyesight. He was evacuated to Sverdlovsk.
In November 1942, he took 2nd place, behind Smyslov, in the Moscow Open, winning 9, drawing 4, losing 2.
In 1943 he played in a tournament in Sverdlovsk and took 5th place. That year he got married. He took 3rd in the 13th USSR Championship.
In 1945 he took 2nd place in the 14th USSR championship, behind Botvinnik. He won 9, drew 6, lost 2. He was awarded the Grandmaster title in the USSR. He played on 3rd board of the USSR-USA radio match. He drew his first game with Fine and defeated him in the 2nd game. He was awarded a prize for the best game of the match.
In 1946 his daughter Tatiana was born. She later married David Bronstein, 18 years older than her. In 1946 he made his first international debut in Groningen and tied for 6th-7th.
In 1947 he took 2nd place in the 15th USSR championship, behind Keres. He won 7 and drew 12 games.
In 1948 he placed 3rd in the Saltsjobaden (Stockholm) interzonal with 6 wins, 12 draws, and 1 loss. The winner was David Bronstein, followed by Szabo.
In April 1950 he tied for 1st place with Bronstein in the Candidates tournament in Budapest, but lost the play-off to Bronstein in Moscow. He missed a win in the 13th game that would have advanced Boleslavsky to the world championship match with Botvinnik.
In 1950 he was given the International Grandmaster title.
In 1951 he was Bronstein's 2nd against his match with Botvinnik for the world championship.
In 1952 he scored 7 out of 8 at the Helsinki Olympiad.
In 1953 he participated in the Candidates tournament in Zurich. He ended up in 10-11th place.
In 1955 his son, Stanilav, was born.
In 1956 he was the second for Smyslov.
In 1957 he published "Izbrannye partii" containg some of his best games.
In 1961 he played in his last USSR championship. He took 1st place at an international tournament in Debrecen.
In 1962 he was the second for all 5 Soviet representatives at the Curacao candidates tournament.
He was world champion Petrosian's 2nd from 1963 to 1969.
In 1964 he took 2nd, behind Smyslov, at Stockholm.
In 1968 he captained the USSR students' team championship which won the world championship.
His last tournament appearance was in Minsk in 1971. He was 52.
He died in Minsk on Feb 15, 1977 at the age of 57.