Klaverjassen is the Dutch name for a popular traditional four player trick-tacking card game.

The name refers to the 'jas' (Jack) being the highest value trump card (as in other card games from the Jass family like Belote), and 'klaver' (clubs, or literally: clover).

Using the piquet deck of 32 cards (7 to Ace of 4 suits), players try to score points in two teams, with partners sitting opposite.

Trump suit for the hand is traditionally determined by turning from the deck of low cards 2-6.

Alternatively, trump suit can be determined by the first player after the dealer, who then must play.

Two important variants exist with regards to the obligation to trump. Rotterdam rules force a player who cannot follow suit to trump if possible, even if the player's partner is heading the trick. Amsterdam rules allow a player to choose not to trump if his partner currently heads the trick.

When playing Amsterdams, undertrumping is only allowed when it cannot be avoided by any other means.