Four-deal Bridge is a form of Rubber Bridge much played in clubs and well suited to home play. Long rubbers are avoided; extra players need wait no longer than the time (typically 20 minutes) required to complete four deals. The game is also called Chicago (for the city in which it originated).
Vulnerability is not determined by previous scores but by the following schedule:
First deal: neither side vulnerable.
Second and third deals: dealer’s side vulnerable, the other side not vulnerable. By mutual agreement, the vulnerability on the second and third deals may be switched.
Fourth deal: both sides vulnerable.
Each hand is scored duplicate style (2 making 3 is 90, 4H vulnerable is 620, etc.).
A partscore or scores made previously may be combined with a partscore made in the current deal to complete a game of 100 or more trick points. The game premium is determined by the vulnerability on that deal of the side that completes the game. When a side makes or completes a game, no previous partscore of either side may thereafter be counted toward game. A side that makes a partscore in the fourth deal, if the partscore is not sufficient to complete a game, receives a premium of 100 points. This premium is scored whether or not the same side or the other side has an uncompleted partscore.
There is no separate premium for making a partscore in any other circumstance.
A multiple of four hands can be played, repeating the sequence of vulnerabilities as often as necessary. The result is simply the total score over the deals played.
For an alternative scoring method for four-deal bridge, please refer to the Laws of Rubber Bridge.