Using standard bidding these sequences are used to support partner's opening Major suit bid.
  • 6-10 points: raise to 2-level
  • 11-12 points: jump to 3-level
  • 0-10 points: jump to game with 5 trumps (preemptive)
  • 13+ points: bid a new suit, then jump to game
The Jacoby 2NT Convention replaces that last sequence with a powerful method for forcing to the game-level while making it much easier to reach slam.

After an opening 1♠ or 1♥ bid, a jump to 2NT promises at least 13 points and at least 4 trumps. Of course you give up the old meaning of a jump to 2NT - the 13-15 point balanced hand. The Jacoby 2NT response absolutely forces the partnership to game and sets the trump suit at the same time.

Much of the power of Jacoby 2NT arises with Opener's second bid, where she describes her opening bid:
(Bids assume 1♠ - 2NT. It works the same with 1♥ - 2NT.)
  • 4♠ : minimum opening, no singleton or void, no interest in slam
  • 4 of a suit : a good second 5-card suit
  • 3 of a suit : singleton or void in the suit
  • 3♠ : stronger than minimum, 6-card suit, no singleton/void
  • 3NT : stronger than minimum, 5-card suit, no singleton/void
Following this description Responder usually takes the controls, either passing Opener's signoff game bid, bidding game himself, or making a move toward slam. The most common move toward slam at this point would be a control-showing cue-bid, bidding a suit where he holds the Ace or void.

While Jacoby 2NT is an excellent convention on its own, it is even better when used in conjunction with the Splinter Bid convention.

Combined Jacoby 2NT / Splinter Bid lesson available.