This article focuses on the five most common bacterial enteropathogens of the developed world—Helicobacter pylori, Escherichia coli, Shigella, Salmonella, and Campylobacter—from the perspective of how they cause disease and how they relate to each other. Basic and recurring themes of bacterial pathogenesis, including mechanisms of entry, methods of adherence, sites of cellular injury, role of toxins, and how pathogens acquire particular virulence traits (and antimicrobial resistance), are discussed.