Doubling Opponents 3NT

We Open

1. Leader's bid suit

1	1NT	2	3NT
Dbl

Partner should lead a diamond

2. Doubler's bid suit

1	1	Pass	3
Pass	3NT	Pass	Pass
Dbl

Lead partner's Club suit

3. Dummy's first bid (or shown) real suit

1	Pass	1	Pass
1NT	Pass	Pass	Dbl

No bidding on your side, so Lead dummy's Spade suit

4. If no real suits have been bid, lead weaker major suit

1NT

Pass

3NT

Dbl

Lead your weak, short major

This treatment is fairly standard, also recited at the ACBL website with the following twist: when no suit has been bid, the double shows a solid suit which can take five tricks if the opening leader can find it. Without a clue, the opening leader will tend to lead a short major suit.

Before moving on, let's clarify one point about #3 - leading dummy's first bid (or shown) real suit. What's with the "or shown" wording? Say the auction goes:

1NT	Pass	2	Pass
2	Pass	3NT	Dbl

The suit shown, or more correctly, suit implied by responder/dummy was the Heart suit. Thus, partner's double asks for the dummy's Heart suit, not the leader's shortest suit nor the dummy's artificial suit (Clubs).

We Overcall

When you overcall and partner denies support at the 2 level and belatedly doubles opponents' Notrump contract, lead the dummy's first bid suit.

1	1	1	Pass
1NT	Pass	2NT	Pass
3NT	Pass	Pass	Dbl

Partner denies support so lead a Spade, dummy's first bid suit

However, when it was not feasible for partner to support your suit at the 2 level (Left Hand Opponent bids above your suit at the 2 level) and Right Hand Opponent balances in Notrump, lead your overcall suit.

1	1	3	Pass
3NT	Pass	Pass	Dbl

Partner cannot show 2 level support so lead your suit (Hearts). Partner has useful cards

(When partner bids a major and later doubles 3 Notrump, lead your short unbid minor suit, ergo a lead inhibiting double! Partner has a 2 suited hand, looking to promote an honor sequence in the side suit.

1	1	1NT	Pass
2NT	Pass	3NT	Pass
Pass	Dbl

Lead a short minor suit

Here's the finale - when all four players have bid a suit and partner subsequently doubles their 3NT contract:

1) lead the dummy's first bid suit if it was at the 1 level,

1	1	1	2
2NT	Pass	3NT	Dbl

Dummy's 1st bid was at the 1 level so lead a Spade, dummy's 1st suit

Memory Aid: Lead dummy's anticipated four card suit

2) lead partner's suit if the dummy's first bid was at the 2 level.

1	1	2	2
2NT	Pass	3NT	Dbl

Dummy's 1st bid was at 2 the level so lead a Diamond, partner's suit