MK-Ultra was a top-secret CIA project in which the agency conducted hundreds of clandestine experiments—sometimes on unwitting U.S. citizens—to assess the potential use of LSD and other drugs for mind control, information gathering and psychological torture. Though Project MK-Ultra lasted from 1953 until about 1973, details of the illicit program didn’t become public until 1975, during a congressional investigation into widespread illegal CIA activities within the United States and around the world.