Recent advances have revealed new insights in cytokine regulation of inflammatory responses. TGFbeta acting together with pro-inflammatory cytokines such as IL-6 promotes lineage commitment of RORgamma-dependent Th17 cells. IL-23--a member of the IL-12 family--activates the effector function of Th17 cells to promote skin, lung, and mucosal immunity. However, when dysregulated, these cells are important players in autoimmune inflammation. Unexpectedly, IL-27--another IL-12 family member--plays an opposing role by inducing IL-10 production as well as downregulating both Th17 and Th1-mediated immune pathologies.