ACBL's official Alert Procedure runs 14 dense pages of rules and examples — useful as a reference, but not the easiest way to learn practical alerting at the table. This page pulls out what actually matters for club-level games: the core idea behind Alerting, the calls you'll run into most often, and where to look if you need the full detail. Nothing here overrides the official document — if the two ever disagree, ACBL's version wins.

The one idea that explains almost everything

An Alert exists to warn your opponents that a call doesn't mean what it looks like it means. That leads to one simple default:

Almost every specific rule in the official document is really just a named exception to one of those two defaults — a natural bid that turns out to need an Alert because its range is surprising, or an artificial bid that's so standard everyone already expects it, so it doesn't get an Alert. If you're ever unsure, ACBL's own advice is: Alert it. A missed Alert can cost you the board; an unnecessary one costs nothing.

Alert vs. Announcement — they're not the same thing

Both exist to warn the opponents, but they work differently, and mixing them up is one of the most common mistakes at the table. On the ACBL convention card, Alerts are marked in red, Announcements in blue.

An Alert:

Say the word “Alert” out loud and tap the Alert strip (or show the Alert card) in the bidding box. DO NOT explain anything yet — you're just flagging that something unexpected happened. If an opponent wants to know more, at their turn to call they can ask “Please explain,” and ONLY THEN does the player who alerted describe the meaning — you can never explain your own bid.

An Announcement:

The same physical action — tap the Alert strip or show the Alert card — except instead of saying “Alert” and waiting to be asked, you say a specific short phrase immediately, whether or not the opponents ask for it: “Fifteen to seventeen” right after partner opens 1NT, or “Hearts” after a transfer bid. Only a handful of situations call for an Announcement instead of a plain Alert — the list is short enough to just memorize, and it's below.

Three lists worth knowing cold

This is the part that actually matters at the table, and it's also the part almost everyone gets wrong in the same direction: assuming a well-known convention needs an Alert when ACBL has specifically decided it doesn't. If a convention you play isn't on any of these three lists, fall back on the general rule above — artificial means Alert, natural means don't — or just ask your director.

One more thing: when asked to explain, don't just name the convention — explain what it actually means. Instead of saying “Jacoby 2NT,” say “A game-forcing raise of partner's major, with four or more card support.”

Keep this in mind: Alerts and Announcements are for your opponents, not you. They are not part of your own bidding system, and it's unethical to listen to your partner's Alerts or explanations and use them to guide your own bidding or play.

The rules, condensed

Natural bids and passes:

Not Alerted, with a short list of exceptions where the range or meaning is wider than it looks — a strong 2♣ opening, a 2- or 3-level opening that could occasionally hold 12+ points, a preempt when there's another way to show the same suit at the same level, a suit bid that implies a longer suit is coming later, or a notrump opening that's always built around a long suit. A pass gets Alerted only if it's forcing when your side hasn't shown any strength yet, if it shows extra strength for the auction so far, or if it shows length in a suit nobody at the table has bid.

Artificial bids:

Alerted by default — that's the whole point of calling them artificial. The exceptions are the small set of artificial calls that are so universally expected that naming them would tell the opponents nothing new: a strong artificial 2♣ opening itself, certain cuebids that only repeat information already on the table, and a handful of similar cases spelled out in the official document.

Doubles:

Alerted by default below 3NT — except an ordinary takeout double, a double of a notrump opening (which is assumed to be penalty or card-showing), and a double of a purely artificial opening bid (which can't be a normal takeout double, so it needs no warning that it's unusual). A double of 3NT or higher is Alerted only if it specifically asks for — or against — a particular suit to be led.

Redoubles:

Alerted by default — except the everyday ones: a redouble that just shows general strength and a wish to play the current contract, one that shows length or strength in partner's suit, one made in the balancing seat suggesting a different contract, or one showing control in the suit that was doubled.

Two situations most club players can skip

Delayed Alerts:

If an Alertable bid happens at or after opener's rebid and the auction reaches 3NT or higher, the Alert itself is put off until the end of the auction rather than interrupting a high-level auction — this mostly comes up with slam-going sequences like keycard ask-and-response. Passes, doubles, and redoubles are never delayed, no matter how high the auction goes.

Pre-Alerts:

Before the first board of a match, a partnership must warn the opponents up front if they play an opening that isn't Natural or that's Forcing, a canapé system, different methods depending on seat or vulnerability, or an artificial preempt below 3NT. This is aimed at partnerships playing something like Precision or another strong-club system — most NVBA club games won't need it, but if you do play one of these, the warning has to come before bidding starts, not partway through.

Full detail

This page leaves out most of the official document's worked examples and every rule for uncommon systems. For the complete, authoritative rules — including the exact wording, every listed exception, and the full set of examples — see ACBL's Alert Procedure (effective February 16, 2026).