This work contains a selection of key articles from volumes 235 and 236 of Methods in Enzymology. It presents in benchtop format, assays and methods used to identify and characterize determinants of bacterial virulence. The book features: examples of in vitro systems to determine bacterial virulence; classical and molecular approaches to identify bacterial strains and components involved in virulence; molecular approaches to study genetics and regulation in pathogenic bacteria; and molecular and cellular interaction of bacterial pathogens with host immune system.