Pathogenesis refers to both the mechanisms used by bacteria to cause infection and those used to cause disease. This seminar course will provide an overview of the numerous virulence factors used by bacteria in these processes and how they allow bacteria to withstand the action of host defense mechanisms in the development of disease. The action of these mechanisms will be explored at both the cellular and the molecular level with an additional focus on the scientific approaches used to investigate them. Current issues in the field will also be discussed, including antibiotic resistance, emerging infectious diseases, and vaccine development.