S&D often refers to the Progressive Alliance of Socialists and Democrats. It may also refer to:
Scratch & Dig, a measure of Surface imperfections of optics Search and destroy, a military strategy, notoriously in the Vietnam War Silver & Deming, reduced-shank drill bits Somerset & Dorset Joint Railway, English railway line Speech and debate, e.g. in debating societies Spybot – Search & Destroy, a spyware and adware removal program for Windows Supply and demand, an economic model of price determination in a market
See also S&DR, the Stockton and Darlington Railway D&S (disambiguation)