Immunofluorescence (IF) is an important technique used in the diagnosis of many infectious diseases. In virology, it has proven to be particularly suited to detecting antibody directed against newly emerging viruses able to be cultivated in cell culture. It permits visualization of antibody and allows for antibody class to be determined which is critical to understanding the timing of infection. The procedure used to determine IgG, IgA, and IgM antibody directed against SARS-CoV-2 in humans is described in this chapter. These methods were developed for routine diagnosis of SARS-CoV-2 infection in Australia at the start of the global pandemic in 2020.