The Health and Safety Laboratory (HASL) of the Atomic Energy Commission has provided much of the data on exposure assessment in uranium contractor facilities and on fallout radionuclides in the environment. The research performed in the beryllium industry 1947-1949 led to establishment of the protection standards that exist to this day. This laboratory was formed in 1947, as part of the Medical Division of the New York Operations Office, directed by B.S. Wolf. HASL was directed initially by Merril Eisenbud and subsequently by S. Allen Lough and John Harley. The history of the Laboratory is traced from its beginning, and the projects described that led to HASL's reputation as a trouble-shooting arm of the Atomic Energy Commission.