The obligate intracellular protozoan parasite Toxoplasma gondii can infect any nucleated cell from a warm-blooded host. However, its interaction with host macrophages plays a critical role in shaping the immune response during infection. Therefore, assessing Toxoplasma–macrophage interactions at a cellular level is important. In this chapter, we describe assays that can be used to characterize Toxoplasma–macrophage interactions. These assays can also be used to evaluate other host–pathogen interactions. We describe multiplex approaches for measuring arginase activity, indoleamine 2,3 dioxygenase activity, cell death, and parasite growth during Toxoplasma–macrophage interactions. These assays can be used to compare how different Toxoplasma strains differ in their interaction with macrophages, and we describe how to properly assess Toxoplasma strain differences in Toxoplasma–macrophage interactions.