Rubinstein flourished especially from 1907 to 1912. Beginning from his win at Karlovy Vary in 1907, through a shared win at St. Petersburg in the same year, he culminated it in a record string of wins in 1912. He won five consecutive major tournaments that year: San Sebastian, Piešťany, Breslau (the German championship), Warsaw and Vilnius (although none of these events included Lasker or Capablanca). Some believe that he was better than world champion Emanuel Lasker at this time. Ratings from Chessmetrics support this conclusion, placing him as world #1 between mid 1912 and mid 1914. Reuben Fine, on the other hand, believed he was not quite as strong as Lasker, and was also eclipsed by José Raúl Capablanca after 1911.
At the time when it was common for the reigning world champion to handpick his challengers, Rubinstein was never given a chance to play Lasker for the world chess championship because he was unable to raise enough money to meet Lasker's financial demands. His plans were damaged by a poor showing at the St. Petersburg in 1914 (not placing in the top five). A match with Lasker was arranged for October 1914, but it never took place because of the outbreak of World War I.
After the war Rubinstein was still an elite grandmaster, but his results lacked their previous formidable consistency. Nevertheless, he won at Vienna in 1922, ahead of future world champion Alexander Alekhine, and was the leader of the Polish team that won the Chess Olympiad at Hamburg in 1930 with a superb record of thirteen wins and four draws. A year later he won an Olympic silver.
Although he lived for almost 30 years afterwards, he left behind no literary heritage like the other great grandmasters, which may be attributed to his mental problems.
He originated the Rubinstein System against the Tarrasch Defense variation of the Queen's Gambit Declined: 1.d4 d5 2.Nf3 c5 3.c4 e6 4.cxd5 exd5 5.Nc3 Nc6 6.g3 Nf6 7.Bg2 cxd4 8.Nxd4 Qb6 (Rubinstein - Tarrasch, 1912). He is also credited with inventing the Meran Variation, which stems from the Queen's Gambit Declined but reaches a position of the Queen's Gambit Accepted, with Black one move ahead.
Today, he certainly has no shortage of lines named for him. The "Rubinstein Attack" often refers to 1 d4 d5 2 c4 e6 3 Nc3 Nf6 4 Bg5 Be7 5 e3 0-0 6 Nf3 Nbd7 7 Qc2. The Rubinstein Variation of the French Defence arises after 1 e4 e6 2 d4 d5 3 Nc3 (or 3 Nd2) dxe4 4 Nxe4. The Rubinstein Variation of the Nimzo-Indian is the most popular non-classical line of the Nimzo-Indian : 1.d4 Nf6 2.c4 e6 3.Nc3 Bb4 4.e3. Of course, there is also the Rubinstein Variation of the Four Knights Game which arises after 1 e4 e5 2 Nf3 Nc6 3 Nc3 Nf6 4 Bb5 Nd4, and the Rubinstein Variation of the Symmetrical English, 1. c4 c5 2. Nc3 Nf6 3. g3 d5 4. cxd5 Nxd5 5. Bg2 Nc7, a highly complex system which is very popular at the grandmaster level.