Peter E. Vaillancourt presents a collection of popular and emerging methodologies that take advantage of E. coli's ability to quickly and inexpensively express recombinant proteins. The authors focus on two areas of interest: the use of E. coli vectors and strains for production of pure, functional protein, and the use of E. coli as host for the functional screening of large collections of proteins and peptides. Among the cutting-edge techniques demonstrated are those for rapid high-level expression and purification of soluble and functional recombinant protein and those essential to functional genomics, proteomics, and protein engineering.