Many Bridge players think that the Negative Double is an advanced level Convention and that it is too difficult for them to use. They are wrong. Think of it as a Takeout Double for Responder.

The Negative Double got started from this situation:
Partner opens 1♣, (for example), and you have 8 or 9 points and a ♥ suit. You were just getting ready to respond 1♥ when the guy in front of you Overcalls 1♠. Uh oh. You can no longer say 1♥ and you don't have the 11 points needed to bid a new suit at the 2-level. You are stuck - UNLESS YOU PLAY NEGATIVE DOUBLES.

But if you do play Negative Doubles then all you have to do is double. This says: "Partner, I was planning to bid 1♥, but that intervening bid prevented me from doing so."

Although the Negative Double can be used to indicate minor suits, it is mostly used to show Majors:
  • 1♣/1♦ - (1♠) - Dbl : shows 4 or more ♥s
  • 1♣/1♦ - (1♥) - Dbl : shows exactly 4 ♠s
  • 1♣/1♦ - (1♥) -  1♠ : shows 5 or more ♠s
The Negative Double is a really worthwhile Convention. But there is a downside. If you add the Negative Double to your partnership Convention list you will no longer have the ability for Opener's partner to make a Penalty Double of an intervening Overcall. You have to choose one or the other.

Lesson available.