The knowledge of Th17 cells and other cell populations which secrete IL-17A, and/or IL-22 has expanded tremendously since the publication of the first edition "Th17 Cells: Role in Inflammation and Autoimmune Disease" in 2008. The present volume has been completely revised with the addition of new chapters on the IL-17 receptor family and signaling, and an in-depth review of IL-22 and innate lymphoid cells. The differentiation of naïve T cells into regulatory T cells and Th17 cells as well as the plasticity of Th17 cells is discussed.