It is important to remember that Acol is more a state of mind than a bidding system. If you play a 5 card major strong NT style (such as sayc) then there’s only one "correct" opening bid. This is not true for Acol, one frequently has a choice. It is also true that Acol has come a long way from the days when it was played in Acol Road, N London in 1934. So what this document sets out to do is show the variants available; the foundation stones from which you can quickly agree a system with a pick up partner.

1-level structure: This is what Acol is all about. What you do with your 2-bids is almost independent of this structure.

1NT is usually 12-14, and assume it is unless you agree otherwise, 5 card minor is ok (wkNT);
15-17 is (stNT),
Stayman is always played, and you should assume that calls of 2D and 2H are transfers (rsts)

1N P 2S is a problem and you need to discuss this, options are:
* 11 points balanced, partner bids 2NT with 12 or 13, and a 4-card suit up the line to 3N with 14 (11)
* weak take out to a minor, partner bids 3c and you pass or correct (wto minor)
* it shows clubs, but this would be specifically agreed (4suitxfrs)

1N P 2N is fine, as it's defined by the choice 1N P 2S.
* It’s natural invitational, 12 pts if you play (11), 11-12 if you play (wto minor)
* or it shows Ds if you’ve agreed (4suitxfrs)

1N P 3-of-a-suit is game forcing unless you’ve agreed otherwise.

1-of-a-suit is about 12-19 and DENIES the ability to open 1NT.
* Add a point for each card after the fourth in each suit
* so a 5-5 should add 2 points, as would a 6-bagger

Open your longest suit. This is so gothic for sayc players. What can I say?
* 5-5 distribution. Open the higher ranking (poss 1C with about 15 with C&S)
* 4-4 distribution. This is the crux. Open the higher ranking unless they’re both black or both majors.
...............But in a way it doesn’t really matter
* 4-4-4-1 distribution. Single C, 1H; single D, 1C; single H, 1D; single S 1D (some open 1H)

Responding to 1-of-a-suit:
* Limit bids 1NT (6-9), 2NT(12), 3NT(13-15); with 10-11 you can bid 1/1 or 2/1 and wait developments
* Limit raises; but raise to the 4-level is pre-emptive with 5 or 6 cards.

* 1/1 6+, respond 4-card suits up-the-line, rebid 1N 15-17, 2N 18-19, 3N running suit (other methods in use)
* 2/1 about 9+ with some fit for partner else 10+. Partner’s new suit should be forcing,
....... but suit rebid, or raise are NF
....... 2NT rebid shows 15-16, and is almost forcing; 3NT is 17-19

NB if you’re playing stNT then the minimum rebids show 12-14, so 2/1 should be a point stronger.

A simple new suit rebid may be 4-4 at the 1-level, but shows 5-4 if taken at the 2-level. (but see reverses)
Reverses after 1/1 should be about 18-19 (trust me), after 2/1 about 16-19.
A reverse guarantees 5 cards in the first suit, and usually 4 in the second
* try xx AKJxx Qxx AKx 1H 2D 3C!