Publisher Summary Arthropod parasites are important pathogens of laboratory mice. Arthropod infestation can alter host behavior and physiology—thereby, introducing unwanted variability into research data. Fortunately, however, they are also uncommon in well-managed animal facilities. Improvements in laboratory animal husbandry practices, pathogen surveillance, and treatment options have dramatically decreased the incidence of arthropod infestation. In particular, improvements in animal husbandry practices have interrupted the life cycles of many arthropods, especially those that spend portions of their life cycle off the host. Laboratory mice are susceptible to infestation with a wide range of arthropod parasites. The relatively few parasitic arthropods likely to be found in modern animal facilities constitute the primary focus of this chapter. It should be noted, however, that changes in the genetic makeup of laboratory mice might expand the scope of parasite infestations. Many genetically modified mice are immunedeficient and may be more permissive of infestation by arthropod parasites.