In chess, the Cambridge Springs Defense (or less commonly, the Pillsbury Variation) is a variation of the Queen's Gambit Declined that begins with the moves: Black breaks the pin on the h4–d8 diagonal and forms a pin of their own on the c3-knight (exploiting the absence of the White's queen bishop from the queenside).

The main line continues 7.Nd2 Bb4 with the threat of ...Ne4 and pressure along the a5–e1 diagonal.

The name derives from a 1904 tournament in Cambridge Springs, Pennsylvania, in which the defense was used several times.

Practitioners of the opening have included Efim Bogoljubov, Vasily Smyslov, Garry Kasparov, and Magnus Carlsen.

The line remains popular among amateurs because there are several traps White must avoid.