Toxoplasma has evolved complex mechanisms for very intricate cross-talk with the host cells in which it resides. Host cells infected with Toxoplasma gondii undergo profound physiological and morphological changes. These changes result from a combination of the host cell's responses to the parasite, and the parasite's attempts to convert the host cell into a suitable growth environment. This chapter discusses the known Toxoplasma induced alterations in host-cell biology, the scarce data on their mechanisms, and their potential mediators. Delineating how Toxoplasma modifies the host cell and how the modifications contribute to parasite survival increase the understanding not only of the relationship between Toxoplasma and its host but also of host processes that otherwise might not ever be revealed. This chapter reviews the characterized changes in host-cell biology resulting from Toxoplasma infection and focuses on alterations that appear to be actively mediated by the parasite to promote its intracellular replication and eventual dissemination. More specifically, these alterations facilitate parasite nutrient scavenging, enhance host-cell survival, and titrate the immune response to allow an infection that does not overwhelm the host.