Listeria monocytogenes infection in mice is a highly prolific model of bacterial infection. Several in vivo imaging approaches have been used to study host cell dynamics in response to infection, including bioluminescence imaging, confocal microscopy and two-photon microscopy, The application of in vivo imaging to study transgenic mouse models is providing unprecedented opportunities to test specific molecular mechanistic theories about how the host immune response unfolds. In complementary studies, in vivo imaging can be performed using genetically engineered bacterial mutants to assess the impact of specific virulence factors in host cell invasion and pathogenesis. The purpose of this chapter is to provide a general rationale for why in vivo imaging is important, provide an overview of various techniques highlighting the strengths and weaknesses of each, and provide examples of how various imaging techniques have been used to study Listeria infection. Lastly, our goal is to make the reader aware of the tremendous potential these approaches hold for studying host-pathogen interactions.