Standard American.

This is not the textbook Standard American of decades past. It is the modern approach the expert game has settled on, upgraded in the places that decide contracts: the notrump structure carries a championship convention card, the minor openings play inverted raises, the major openings gain the game-forcing two-over-one with the forcing notrump and Two-Way Drury around it, and the competitive card runs from Lebensohl to splinters. Same five-card-major skeleton, modern muscles.

One precision worth learning early: the two-over-one response forces to game only from an unpassed hand - a hand that already passed cannot logically insist on game, so its two-level bids mean other things (see the game-force rule and Two-Way Drury below). Pick Standard American from the system selector on the practice screen and every call is graded against exactly what this page says.

Every range below assumes the same vocabulary. It's worth being precise about it, because most bidding disagreements between partners turn out to be arithmetic disagreements in disguise.

Two conventions decide the rest. Five-card majors means 1♥ and 1♠ always promise five, so a four-card major is opened one of a minor and shown later. Better minor means with no five-card major you open the longer minor, and with equal length, 1♦ on four-four, 1♣ on three-three. That 3-3 case is exactly why a 1♣ opening can be a three-card suit.

Opening 1♥ rather than 1♠ carries an extra message: with five-five in the majors you open the higher, so 1♥ denies five spades. 1♠ makes no such promise about hearts. Small asymmetries like this are what let partner draw real inferences later in the auction.

A new-suit response at the two level to partner's one-level suit opening (by a hand that hasn't already passed) is forcing to game. No matter what happens for the rest of the auction, the partnership has agreed not to stop below game (barring a disaster uncovered along the way, like finding a combined 18 HCP and an 8-card fit missing four top honors).

The one standard exception: a passed hand. If responder has already passed as dealer or in second/third seat, a later two-over-one is merely competitive and constructive, not forcing: you can't force to game with a hand that already denied opening values.

The forcing notrump is the other half of the game-force rule: every hand of 5-11 that cannot raise and has no suit to show at the one level starts here, and opener must bid again. Opener's rebid tells strength and shape at once, and with nothing to say, the convention is a three-card minor.

Responder's second bid

The 1NT response said almost nothing, so the second call carries the real message: weak hands take a preference or sign off, and the 10-11 hands invite.

In competition the convention is off: over an overcall or a double, 1NT reverts to its natural, non-forcing meaning with a stopper in their suit. And it applies only to the majors: a 1NT response to 1♣ or 1♦ is the standard 6-10.

The commonest way to miss a game is to invite one you could have bid. Partner opened, so the moment responder can count 25 between the hands the question is not whether to play game but which one.

Because the direct jump raise is weak in this system, the game-forcing raise needs somewhere else to live, and Jacoby 2NT is it. Keeping the strong raise low is the whole point: it leaves the entire three level free for opener to describe shortness before the partnership commits.

Note the inversion. Over a major, the jump raise is the weak one and the strong raise goes through 2NT. Over a minor, it's the reverse: the cheap raise is strong and forcing, the jump is preemptive. The logic is that minor-suit games are rare and distant, so the partnership needs room to explore 3NT, and the strong raise is the one that needs the room.

Once a two-over-one response has forced the auction to game, opener no longer needs to jump the bidding to show extra strength: there's no danger of the auction stopping too low. That turns opener's rebids into plain, natural description:

Whenever our side's first three bids all come at the one level - 1♣ – 1♠ – 1NT, 1♦ – 1♥ – 1♠, any of them, uncontested - responder's 2♣ and 2♦ stop being natural. The convention splits every hand into three lanes: sign off cheaply, invite through 2♣, or force to game with 2♦. Neither bid says anything about the suit it names.

When the auction has touched three of the four suits and responder bids the last, untouched suit, it is artificial: fourth suit forcing. One family of auctions is carved out first: when all three of our bids came at the one level, XYZ (above) owns responder's 2♣ and 2♦ regardless of the suits, and the fourth-suit machinery applies to the rest. It may not be a suit at all - it says nothing about the suit it names - and it activates the game force after any opening, major or minor, whether the fourth suit arrives at the two level (1♥ – 1♠ – 2♣ – 2♦) or the three level (1♦ – 1♠ – 2♥ – 3♣). It exists to create the force: when a two-over-one has already set one, the fourth suit is a natural bid again - a real suit and extra strength - because under a live force every call is free and nothing artificial is needed. Opener keeps describing: a second suit, three-card support for responder's suit, and otherwise notrump - the default, with no stopper test, because unless the opponents have intervened there is no asking-for-stoppers paradigm in this system. And with no eight-card major fit anywhere, 3NT is the default game - a minor-suit game enters the picture only for an unbalanced hand with a nine-card minor fit and a void or singleton in a major partner has never bid - partner's silence there caps them at three cards, so that suit is wide open in notrump and ruffable in the fit.

2♦ opens the hand with exactly four spades and five or six hearts, 11-15 HCP - the shape with no comfortable rebid after a 1♥ opening. Responder knows both majors and the range at once, so most responses are signoffs; 2NT is the one forcing call, and opener's answer pins the exact shape.

Every other opening is limited. 2♣ is the one bid that isn't, which is why it's artificial: it buys a round of bidding in which opener can describe a hand too strong to risk being passed out.

Slam bidding is a different activity from the rest of the auction. Everywhere else you are establishing how strong the hands are; here strength is largely known and the question is whether specific cards are present. That is why the tools are asking conventions rather than descriptive bids.

Roman Key Card, 1430. The responses are worth knowing cold — miscounting them is the single most expensive error in slam bidding, because the penalty for getting it wrong is a slam off two aces:

What the asker does with the answer matters as much as the answer itself:

When not to ask. Roman Key Card is a precision instrument for one specific question, and reaching for it reflexively is how good hands get bid badly:

Before reaching for an ace-ask at all, cuebid. Cuebidding finds the duplicated values Blackwood cannot see: two hands with 33 combined points and their losers in the same suit still cannot make twelve tricks, and no count of aces will ever reveal that. See Controls for what you are actually counting.

Everything below is part of THIS system, not a separate subject: when you open and the opponents interfere, the conventions that protect the auction - negative doubles, support doubles, the redouble structure, Lebensohl, the forcing pass - are agreements between you and partner, exactly like the openings above. Entering THEIR auction is the different subject, and it lives on the Competitive Bidding page.

When partner opens and RHO overcalls, a double by you is negative: it shows the unbid suit(s) rather than penalty. It's the single most important competitive convention in a 2/1 system: it lets you compete for a fit without jumping the auction past a comfortable level.

When partner opens one of a major and RHO doubles, the ordinary raise structure stops working: a simple raise now covers everything from a hand competing on air to a hand worth an invitation, and opener cannot tell them apart. Their double solves the problem it created: a hand that wanted to bid notrump naturally can redouble instead, which frees both notrump calls to describe raises.

This applies over a major, not a minor. A minor opening does not promise five cards, so raising it is not the known eight-card fit the structure is built on.

Both notrump raises are limited at the top as well as the bottom, which makes opener's next call close to arithmetic: partner has promised a range, and opener knows whether the sum of the two hands reaches game at the bottom of it, only at the top, or not at all.

Responder then answers the trial bid:

The thresholds above are not one number. What a raise is worth depends on the shape far more than on the point count, and the bigger the fit the less the count tells you.

After opener rebids and responder shows a suit, if RHO now doubles or overcalls, opener's double (or redouble, if RHO doubled) is a support double: it shows exactly 3-card support for responder's suit, as opposed to bidding it directly, which would show 4. That precision matters when responder is deciding whether to compete further.

Lebensohl is the standard tool for a natural two-level overcall (2♦, 2♥ or 2♠) of partner's 1NT opening. One distinction runs through the whole convention: a direct three-level call denies a stopper in their suit, and the slow route through the artificial 2NT relay shows one. The game-forcing threshold is about 10 opposite a 15-17 notrump and about 12 opposite Precision's 13-15. The same framework covers their conventional gadgets (DONT, Cappelletti): every such 2♦/2♥/2♠ that promises the suit it names is treated as a natural overcall of that anchor suit, and Lebensohl applies unchanged.

After the relay: 1NT – (2x) – 2NT – pass – 3♣

Opener's 3♣ is compulsory, and responder's next call places the hand.

When your own opening gets overcalled and the auction comes back around to you (partner passed, RHO passed) you're in the reopening seat, a close cousin of balancing seat. With extra shape or strength, especially shortness in the opponents' suit, reopen with a double (showing support for the other suits, exactly like a normal takeout double) rather than let a partscore go by uncontested. Reserve an outright pass for hands with no realistic play for anything else.

Slam auctions are the most attractive time for the opponents to interfere, because your responses are step-based and steps are exactly what a bid takes away. The counters are simple, and completely useless without a prior agreement.

Bridge Sense does not yet grade auctions where the opponents interfere over 4NT — the engine handles ace asks in uncontested auctions only. The conventions are here because you will meet them at the table long before the coach can mark them.