Toxoplasma gondii (Toxo.) is a unicellular protozoan parasite that causes the disease toxoplasmosis. Although toxoplasmosis only shows symptoms in vulnerable patients, such as pregnant women and immunocompromised, over 40 million people are infected in the United States alone1. Studies have shown that calcium induces egress of Toxoplasma gondii in host cells2. Treating Toxo. with calcium ionophore before invading cells may have an effect on motility and how Toxoplasma gondii invades. In this study, Toxo. is treated with calcium before invading the cultured HFF2 host cells. The HFF2 cells are then plated on different substrates stiffnesses of polyacrylamide gels or on glass coverslips without gels (as a control group). Fluorescent microscopy was used to image the invasion of Toxo. into the host cells. The rates are analyzed to determine if Toxo. has decreased invasion in the presence of calcium. Understanding how calcium affects Toxo. may change the way we view invasion and could be useful in reducing invasion in other parasites. This may also be helpful for people with Toxoplasmosis.