This unit describes methods for infecting mice with L. monocytogenes. Optimal media for growth and methods to maintain bacterial virulence by passage through mice are included. Methods for determining the severity of splenic and hepatic infection are detailed, with strategies for distinguishing innate from specific immune responses following L. monocytogenes infection. This infection induces MHC class I-restricted CD8(+) cytolytic T lymphocytes that clear infection and provide long-term immunity. This unit describes methods that can be used for in vitro expansion of L. monocytogenes-specific T cells.