The T-box transcription factor T-bet is most prominently known for its role in production of the cytokine interferon-γ (IFNγ) by effector T cells after infection with Th1-inducing pathogens. Here, we demonstrate additional roles for T-bet during effector T cell responses including an essential function in T cell trafficking to secondary sites of infection during toxoplasmosis. Mice that are deficient in T-bet are unable to survive infection with the intracellular parasite Toxoplasma gondii, and this mortality is caused by uncontrolled parasite replication at secondary sites of infection and is associated with a paucity of T cells at these sites. Additionally, we provide evidence that T-bet is also involved in early events of T cell priming and expansion. Together, the data presented in this thesis provide a better understanding of the diverse roles that T-bet plays in the generation and function of T cell responses during the immune response to T. gondii.