Whether a Weak 2-Bid should be called a Convention or a natural bid is a matter of taste. Here it is considered a Convention because it is more structured than preemptive 3 and 4 bids.

You can open with a Weak 2-Bid whenever your hand matches this:
  • A 6-card suit with some decent strength, maybe 2 or 3 honors
  • 6-11 points, including the 2 points for the fifth and sixth card
  • no outside 4-card Major suit
The suit must be ♠s, s or s. You cannot open with a Weak 2-Bid in ♣s because that bid is reserved for very strong hands. The purpose of the Weak 2-Bid is primarily obstructive, just as with the other Preemptive bids. However, since the bid is so descriptive the Responder will have a pretty easy time with later bids.

There are two different philosophies in responding to a Weak 2-Bid.
One is called RONF for 'Raise is the Only Non Forcing' bid. Basically this means that when the initial Response is either a new suit or Notrump Opener is required to bid again.
The second doesn't have a name, but it says that 2NT is the only forcing bid.

The two methods are different only in how they treat a new suit bid by Responder; Forcing or Non-Forcing. For this topic the second method, 2NT being the only Forcing bid will be used.

Responder needs about 15 or more points to be considering game. With fewer points than that he has two choices.
  • Raise Opener's suit. This is just increasing the obstruction value.
  • Bidding his own suit. This is done only if Responder believes his suit is better.
With a stronger hand Responder usually bids 2NT, forcing Opener to further describe his hand according to the following:
  • 6-8 points : return to 3 of the suit
  • 9-11 points : bid a suit with a 'feature' (an Ace or a King, perhaps a Queen)
  • A K Q x x x suit : bid 3NT
Responder should be in a position to finalize the contract after this bidding sequence.

Lesson available.