Stuart L. Schreiber (born 6 February 1956) is a scientist at Harvard University and the Broad Institute. He has been a pioneer in a field of research named chemical biology for over 20 years. Molecular pharmacology is closely associated with the increasingly common use of small molecules as probes of biology and medicine. Small molecules are the molecules of life most associated with dynamic information flow; these work in concert with the macromolecules (DNA, RNA, proteins) that are the basis for inherited information flow. During the 1980s and '90s, he provided dramatic advances in biology using this approach, and, in the past ten years, his systematization efforts have made this one of the fastest growing areas of life-science research.