American mahjong has one written standard and a thousand local habits. New players cannot tell them apart, and that is where most table arguments come from. This guide separates the two.
Where an official rule actually comes from
Official rules live in exactly two places.
The current year's NMJL card. If a hand is not printed on it, it is not a legal winning hand. That one sentence settles more disputes than anything else in the game.
The League's published rules and bulletins. The written standard the National Mah Jongg League issues alongside the card.
Everything else is a local agreement: what your club does, what the woman at Tuesday open play taught you, what "we've always played." It may be perfectly sensible. It is not official, and a player visiting from another club has no reason to know it.
The one-question test
When a disagreement comes up, ask this: can someone point at it?
An official rule can be pointed at, on the card or in League material. A house rule cannot. It lives in memory and habit. If the answer sounds like "my group has always done it this way," you have your answer, and it is not a rule.
Teach that test to new players before their first game at a table they have not sat at before.
Rules people mistake for house rules
Some things sound optional and are not.
You may not win with a hand that is not on the card. This is the foundation of the game, not a preference. Four sets and a pair means nothing here. The card page shows how lines are printed and read.
Flowers do not bring a replacement tile. Players arriving from Chinese mahjong assume a flower gets exchanged for a new tile. In the American game it does not. It counts as a tile in your hand, and that is the whole story.
The Charleston happens before every hand. The three-pass exchange is part of the game, not a warm-up some tables skip. The Charleston is where hands are decided.
A joker cannot be part of a pair. The most quoted rule in the game and the one that keeps catching people out. Full detail on the joker rules page.
Things that really are local agreements
These vary table to table, and none of them are printed on the card:
- What a point is worth in money. The card prints point values, not dollars. Converting points to cash, and at what rate, is up to the table. See scoring for how points are actually paid.
- Whether you play for anything at all. Plenty of clubs play for points only.
- How the table handles a late arrival or an empty fourth seat.
- What happens after an erroneous Mah Jongg call, beyond the hand being dead. The dead hand rules cover the hand itself. Anything extra is a table matter.
- How long a turn may take, and whether anyone is timing it.
None of these are wrong. They are just yours.
If you host: write it down
Most friction at a mixed table comes from rules nobody wrote down, because everybody assumed they were universal. Six lines on an index card prevent an entire evening of argument:
- Which year's card you are playing.
- What a point is worth, if anything.
- Whether the optional second Charleston is played.
- Any local timing or courtesy expectations.
- What happens when someone is late or the fourth seat is empty.
- Who settles a dispute. Name that person before you need one.
Read it aloud before the first deal. Thirty seconds at the start buys you a quiet evening.
When a disagreement happens anyway
Stop. Do not argue from memory. Look at the card. If the card does not settle it, the host decides for that evening, and the group writes it down for next time. What you do not do is let a dispute become a ruling by whoever speaks loudest.
For the cases that come up again and again, the rulings page collects how they are usually handled.