In 1992, Kleber, with his wife Marian Fischman, co-founded the Substance Abuse Division, one of the leading centers in the country for treatment of such abuse, within the Department of Psychiatry at Columbia University. He was director of the Division, and headed a number of projects on new methods to treat individuals with cocaine, heroin, prescription opioid, alcohol, or marijuana problems. He also co-founded the National Center on Addiction and Substance Abuse at Columbia with Joseph Califano.