All fours is a traditional English card game, once popular in pubs and taverns as well as among the gentry, that flourished as a gambling game until the end of the 19th century. It is a trick-taking card game that was originally designed for two players, but developed variants for more players. According to Charles Cotton, the game originated in Kent, but spread to the whole of England and eventually abroad. It is the eponymous and earliest recorded game of a family that flourished most in 19th century North America and whose progeny include pitch, pedro and cinch, games that even competed with poker and euchre. Nowadays the original game is especially popular in Trinidad and Tobago, but regional variants have also survived in England. The game's "great mark of distinction" is that it gave the name 'jack' to the card previously known as the knave.

The game has a number of unusual features. In trick play, players are allowed to trump instead of following suit even if they could. The title refers to the possibility of winning all four game points for high, low, jack and game for holding (later winning) the highest and lowest trump in play and the jack of trumps and for winning the greatest number of card points.

All fours is among the oldest extant card games in England. Its first known description was in Charles Cotton's Compleat Gamester of 1674, where the game was reported as popular in Kent. It is probably of Dutch ancestry, and is the game that gave the name jack to the card that was originally known only as the knave.

By no later than the 1800s, the game was taken to America and became popular among African Americans on slave plantations. Also called seven up, it gave rise to other variants such as Pitch and Auction Pitch, which probably developed in the New England states, Pedro, and California jack, also known as ligh-low-jack. Modern descendants include don and phat, developed in Britain and Ireland. The game is still played in north-west England and Wales, and it has become the national game of the Republic of Trinidad and Tobago.

The earliest known rules for all fours appear in the 1674 edition of The Compleat Gamester by Charles Cotton. Cotton tells us that "All-Fours is a Game very much play'd in Kent, and very well it may since from thence it drew its first original; and although the game may be lookt upon as trivial and inconsiderable, yet I have known Kentish Gentlemen and others of very considerable note, who have play'd great sums of money at it..." His rules, which are not complete, are as follows.

The game was called all fours from its four point-earning feats: highest, lowest, jack and game. It was a game for two players. The players 'lifted' (i.e. cut) for the deal and the player with the highest put-card won. This presumably meant the highest using the ranking in put i.e. 3-2-A-K-Q-J-10-9-8-7-6-5-4. However, in the rest of the game the cards rank in their natural order (aces high).

The dealer dealt three cards each, beginning with elder hand, and then three more each so that both players had six cards, before turning the next for trump. If the turn-up was a jack, the dealer scored 1 point. If elder did not like his hand, he could 'beg'; if the dealer accepted, elder scored 1 point and threw his cards in; if the dealer refused, he dealt three more cards each and turned another for trump. If the latter was of the same suit, the exercise was repeated.

The scoring card values for game are ace 4, king 3, queen 2, jack 1, and ten 10. Play is not described in detail, except that it seems players had to follow suit, but could renege on doing so if they had a trump. According to McLeod, elder led to the first trick and players had to follow suit or trump, but could not discard unless they could not follow. The higher trump won or, if none were played, the higher card of the led suit. The trick winner led to the next.