What is Two Over One?

Two Over One is the most widely played system, or more properly family of systems, among U.S. tournament bridge players. Two Over One systems include the version popularized by Max Hardy in a series of books from the 80s through the early 2000s and Washington Standard.

Strictly speaking, Two Over One refers to the agreement that a two over one call in an uncontested auction is game forcing, though some players may allow the auction to stop below game under certain specified conditions.

It is normally understood, though, Two Over One as a "system" description refers to systems with the following features:

• 5 card majors - an opening of 1 of a major suit shows 5 or more cards
• Two Over One forcing to game unless the partnership has specified a limited number of conditions under which the partnership can stop below game (typically after 1♦ -2♣ and/or with a minor suit fit and neither partner able to bid notrump)
• 2♣ strong and artificial - 2♣ is the only forcing opening

Other features can vary considerably, but without prior discussion, a pair of experts playing agreeing two over one without further discussion would tend to assume a system including:

• Strong notrump with four-way transfers, Smolen, Texas and lebensohl
• A forcing or semi-forcing 1NT response to 1M
• Jacoby 2NT and Drury in response to 1M
• Inverted minor suit raises and invitational 2NT in response to one of a minor
• 2♦  waiting in response to 2♣ 
• Weak 2s with either Ogust or feature-asking 2NT response
• New Minor Forcing or Two-Way Checkback
• Fourth Suit Artificial and Game Forcing
• Negative doubles through 4♥ or 4♠, with the understanding that high-level negative doubles may often be passed
• Support doubles through 2♥ 
• 0314 or 1430 Roman Key Card Blackwood

A fully developed 2/1 system in an expert partnership will include many more agreements and may extend to hundreds of pages of agreements.

Should I play Two Over One?

There isn't a right or wrong answer to this, but in most systems current played worldwide, including "natural" 5 card major systems, strong club systems, and others, most experts play that a 2/1 response is game forcing. Why? Because it makes things easier. After a game forcing 2/1 call, you no longer have to worry about whether various bids below game are forcing or not. This gives you a lot more leeway to explore for the right game or to explore for slam. It involves some compromises; there are some hands that are bid more easily if 2/1 is not game forcing, but on the whole, it's widely seen as a good trade-off. 

Is it hard to learn and play Two Over One?

Not really. You can basically just agree with your partner that 2/1 is game forcing and bid naturally from there. It is conventional wisdom that you have to play a forcing or a semi-forcing 1NT, but you really don't. (This is not just my view, but that of a substantial proportion of top players.) And you can play 2/1 game forcing without the other bells and whistles that are part of most 2/1 systems, while adding things at your own pace. I'll have much more to say in the coming months about what I recommend adding. For a preview, feel free to email me.