Since the development of cell sorting in the late 1960’s, flow cytometry has been used as a tool to investigate and characterize the immune system. The development of digital instrumentation, affordable solid state lasers, energy transfer fluorochromes, and quantum dots have all contributed to an unprecedented ability to describe fine details of the immune system biology. Moreover, techniques have been developed to measure the inner workings of cells. These include fluorescent reporter reagents, flurogenic substrates, bar coding technologies, and intracellular staining. This has allowed researchers to look at response to stimulation and the activation of signaling pathways of different compartments of the immune system, and process such as the mechanisms of viral fusion. The future holds more promise – we will examine in this talk the potential of three new technologies: Celula’s sorter on a chip, Amnis’ Imagestream imaging flow cytometer, and DVS Sciences CyTOF mass spectroscopy cytometer.