Robert A. Weisberg was a Scientist Emeritus at NCI until the time of his death on 1 September 2011. Previously he was Chief of Microbial Genetics at NICHHD, a position he retired from in 2008. He was a pioneer in the study of the bacteriophage lambda. His research lead to seminal contributions about how bacteriophage lambda integrates into the E. coli chromosome. His laboratory produced the first library of cloned genes, using lambda transducing phages. Weisberg’s work was a combination of biochemical and genetic approaches, and he was an expert in both disciplines.