Helper T cell subsets have evolved to respond to different pathogens, and upon activation secrete distinct sets of cytokines. The discovery and identification of Th17 cells, which develop via a unique lineage from Th1 and Th2 cells, have provided new insights into aspects of immune regulation and host defense that were previously unclear. A key early signaling event upon Ag recognition is elevation of intracellular free Ca 2+, and cytokine expression can be differentially induced depending on the duration, amplitude, and pattern of Ca 2+ signaling. Th1 and Th2 cells can be distinguished by their Ca 2+ profiles, and we provide in this study the first report regarding Ca 2+ signaling in Th17 cells. Th17 cells have a distinct Ca 2+ signaling profile from Th1 and Th2 cells with intermediate sustained Ca 2+ levels and increased oscillations compared with Th2 cells. Elevated intracellular Ca 2+ has been shown to inhibit T cell motility, and we observed that Th17 cells, like Th1 cells, are less motile than Th2 cells. Analysis of NF-AT nuclear localization revealed that Th1 and Th17 cells have significantly higher levels at later time points compared with Th2 cells. Thus, these findings show that Th17 cells, in addition to their distinct cytokine response from Th1 and Th2 cells, display unique patterns of intracellular Ca 2+ signaling and Th1-like motility behavior and nuclear localization of NF-AT.