Partner opens on the one level.

When should you respond 1 or 1 and what does it promise?

HCP: Typically 6+ to respond, but it is okay to have a little less if you have a good suit or an ace and/or decent shape.

After Partner's 1 Opening

Respond in your major (4 or more cards) to partner's 1 opening (with 4-4 in the majors, respond 1; with 5-5, respond 1). In the modern style, ignore (bypass) diamonds unless you have opening bid strength.

After:

West	North	East	YOU
	1	Pass	??

AQ54 A1032 Q42 54	1	Up the line with 4-4 (can't use 2/1 GF after 1).
A9654 AK765 Q42 --	1	Spades first with 5-5.
A3 Q1065 J7654 32	1	Bypass diamonds with this "1-bid hand".
AQ54 A105 AK654 3	1	Show diamonds first (and bid spades later -- since there will be a "later").
Q1076 A32 Q54 1082	1	Don't bypass a 4-card major (don't respond 1NT to show "points").

After Partner's 1 Opening

All the rules/examples above apply. If you have less than opening bid strength, you will always respond in a major (4+ cards) if you have one. But, what if you have a choice between showing a major, or using a 2/1 GF auction? For example, partner opens 1 and you hold:

A1076
32
A2
AKJ65.
Because you have enough strength for a 2/1 response, start with 2. You can find a 4-4 spade fit later if it exists. It makes for a much better auction to establish the game force first. But:

> With 5 (or more) cards in the major, always start with 1 of the major (if you bid 2/1 in a new suit, partner will never get the message that you have 5 in your major when you introduce it later).
> With 4 in the major and 4 in a biddable minor, I strongly recommend starting with the 2/1 GF auction if possible. So, respond 2 to 1 with: K2 K1076 K32 AQJ2.

After:

WEST	NORTH	EAST	YOU
	1	Pass	??

K1076 QJ54 2 AJ76	1	Up the line with 4-4 (not enough strength for 2, GF).
A543 A987 -- KQJ76	2	Get into the 2/1 GF auction at once. You can find a major-suit fit later.
A3 Q10652 2 AQJ32	1	As much as I like 2/1 GF auctions, if you start with 2, partner will never play you for 5 cards in hearts.
A1065 42 32 AJ765	1	Not strong enough for a 2/1 GF auction.

After partner's 1 Opening

If you have 4+ hearts, you would typically ignore spades (maybe bid a really long/strong spade suit).

With 3 hearts, raise (ignore spades) if you have only one bid to make. So, raise 1 to 2 with:

Q8654
K102
32
Q102.

With 3 hearts and enough to bid twice (roughly 11+), you can bid 1 (four or more) and raise hearts next.

With fewer than 3 hearts, use the same scheme as over 1. Prefer a 2/1 GF auction with enough strength and only 4 spades. For example, respond 2 to 1 with:

QJ87
K2
AQ1076
A2.
You can find spades later. But, respond 1 with only:

QJ87
K2
98764
A2.

With 4+ spades (and no 3+ card heart support, but 6-12 points), respond 1.
With 5+ spades (and no 3+ card heart support) always respond 1.

With exactly 4 spades (and no heart support) and GF values and a showable minor, start with 2 of the minor.

After:

WEST	NORTH	EAST	YOU
	1	Pass	??

A872 A542 2 K542	4	Make a Splinter Raise of hearts; ignore the spades.
A872 A542 A2 AQ2	2NT	Jacoby 2NT; ignore the spades.
A1043 2 K76 KJ532	1	Show the spades (1NT would deny 4 spades and you aren't strong enough for a GF 2).
Q983 A A76 KJ1076	2	Enough for a 2/1 GF auction (a 4-4 spade fit can be found later).
K876 42 AKJ8 K72	2	Even with 4-4, better to get into the 2/1 GF auction (a 4-4 spade fit can be found later).
A8762 3 A9832 AQ	1	Don't use 2/1 GF to bypass a 5+ card major

After partner's 1 Opening

This is "off-topic" since you can't respond on the one-level. If you do respond 2, you promise at least 5 cards in hearts. Assuming 2/1 GF, you also promise opening-bid strength.

After the Opponents Double

After the opening bid is doubled, all 1-level responses of 1 or 1 are as above. Usually, responder will redouble with 10+HCP and a balanced hand. So, after:

West	North	East	South
	1	Double	??

South would redouble with:
K1032
KJ2
A102
J32.

With 10+ HCP and an unbalanced hand or long major, usually it is better to eschew the redouble and just make the response you would have made without the double:

WEST	NORTH	EAST	SOUTH
	1	Double	??

South should respond 1 (not redouble) with:
2
KQJ872
A102
J82.

For more on responding, see this book.

For a webinar on 2/1 GF, click here.