In music, a double stop refers to the technique of playing two notes simultaneously on a bowed stringed instrument such as a violin, a viola, a cello, or a double bass. In performing a double stop, two separate strings are bowed or plucked simultaneously. Although the term itself suggests these strings are to be fingered (stopped), in practice one or both strings may be open.

A triple stop is the same technique applied to three strings; a quadruple stop applies to four strings. Double, triple, and quadruple stopping are collectively known as multiple stopping.

Early extensive examples of the double-stop and string chords appear in Carlo Farina's Capriccio Stravagante from 1627, and in certain of the sonatas of Biagio Marini's op. 8 of 1629.

Bowing

On instruments with a curved bridge, it is difficult to bow more than two strings simultaneously. Early treatises make it clear that composers did not expect three notes to be played at once, even though the notes may be written in a way as to suggest this. Playing four notes at once is almost impossible. The normal way of playing three or four note chords is to sound the lower notes briefly and allow them to ring while the bow plays the upper notes (a broken chord). This gives the illusion of a true triple or quadruple stop. In forte, however, it is possible to play three notes at once, especially when bowed toward the fingerboard. With this technique more pressure than usual is needed on the bow, so this cannot be practiced in softer passages. This technique is mainly used in music with great force, such as the cadenza-like solo at the beginning of the last movement of Tchaikovsky's violin concerto.