If you play the American game, the Chinese competition rules will feel like a different species. There is no annual card, no joker, and no Charleston. What there is instead is a fixed book of 81 scoring patterns and a minimum score you must reach before you are allowed to win.
This is the system used at the World Mahjong Championship and at most organised Chinese play, and it is worth understanding even if you never play it — because a lot of what people say about "real" mahjong refers to it.
Where it came from
In July 1998 the Social Sports Guidance Center of the General Administration of Sport of China approved the Mahjong Competition Rules of China (Trial) — 《中国麻将竞赛规则（试行）》 — after more than two years of drafting work. It was published by People's Sports Publishing House.
Note the word trial. The document was never finalised into a permanent national standard, and that fact matters later when you read claims about mahjong's official status in China.
The rulebook's own foreword contains the single most useful sentence anyone has written about mahjong's reputation:
"Mahjong has no necessary connection with gambling… the blame lies not with mahjong itself."Foreword, Mahjong Competition Rules of China (Trial), 1998.
This is worth quoting precisely because it is institutional rather than personal. Everyone from grandmothers to government ministers has been credited with the observation that mahjong is not gambling; the version that can actually be cited comes from a rulebook.
How it plays
The set is 144 tiles — the same 108 suited tiles and 28 honours as the American game, plus eight flowers, and no jokers at all.
Eighty-one scoring patterns, arranged in nine series and twelve value tiers running from 1 point up to 88. The names are the poetry of the game: 大三元 (Big Three Dragons), 十三幺 (Thirteen Orphans), 九蓮宝燈 (Nine Gates), 清一色 (Full Flush), 海底撈月 (Bottom of the Sea).
You need 8 points to go out. This is the rule American players find strangest. You cannot win on a worthless hand; your hand must reach the minimum before it counts. Flowers do not count toward it.
Payments run off an 8-point base, from a 500-point starting stack.
A match is sixteen hands — four rounds of four, with no dealer continuation and mandatory seat rotation, which is designed to cancel out seat luck over a session.
Calls are spoken in Chinese: 吃 (chī, chow), 碰 (pèng, pung), 槓 (gàng, kong), 花 (huā, flower), 和 (hé, win).
The official position on gambling
The rulebook's framing has been consistent for nearly thirty years, and it is more interesting than the usual argument either way. The stated line is:
鼓勵競技麻將、引導休閒麻將、反對賭博麻將 Encourage competitive mahjong, guide recreational mahjong, oppose gambling mahjong.
Three categories, not two. The middle one is the one that gets lost in translation: recreational play is not the enemy, it is something to be guided. It is a considerably more sophisticated position than either prohibition or uncritical promotion.
Two organisations, frequently confused
If you read English-language coverage of competitive mahjong you will find these mixed up constantly. They are not the same body.
The World Mahjong Organization (WMO) was proposed at the third China Mahjong Open in Beijing in October 2005 and is headquartered in Beijing, with roughly thirty member countries. It publishes the international competition rules and runs the World Mahjong Championship. Note: some sources give its founding as 2006 rather than 2005; we are not asserting a year.
The Mahjong International League (MIL) was registered in Lausanne in July 2015 and moved its headquarters to Hangzhou in 2022. MIL created the duplicate format — the same deal played by many pairs, scores compared across the field — which is the same trick that turned bridge into a proper mind sport.
On 5 April 2017, at an IMSA executive meeting in Aarhus, MIL was admitted as a full member of the International Mind Sports Association. That made mahjong the sixth internationally recognised mind sport, alongside bridge, chess, go, xiangqi and draughts. This is the single most concrete thing that can be said about mahjong's sporting legitimacy, and it is a matter of record.
Why an American player should care
Three reasons, in ascending order of usefulness.
It explains the arguments. When someone tells you that the Chinese game is the "real" one, they usually mean some version of this rulebook. Knowing what is actually in it ends the conversation quickly.
The 8-point floor is a genuinely good idea and you can borrow it. American players routinely chase 25-point hands they cannot finish and refuse to abandon. Adopting a personal rule — I do not stay in a hand I cannot plausibly complete — imports the discipline without changing any scoring.
The duplicate format is the future of organised play, and it is coming to the American game eventually. When it does, the players who understand it will have an advantage.
Recommended reading
Annelise Heinz's Mahjong: A Chinese Game and the Making of Modern American Culture (Oxford University Press, 2021) is the strongest single authority in English and is directly relevant to the American story. For the rules themselves, the European Mahjong Association publishes English translations of the MCR scoring tables.