T17 (T-helper-17) cytokine responses have been recently recognized as an important component for the protective immunity produced by vaccination. However, the mechanism by which immune adjuvants induce T17 immunity has not been defined. We have developed a novel mucosal nanoemulsion (NE) adjuvant that produces a robust humoral and T1 cellular immunity. Herein, we demonstrate that immunization with NE adjuvant induces a T17 response to diverse antigens in both outbred and inbred mice. CD86 deficiency had a limited effect on the induction of IL-17, however, double CD80/CD86, CD40, and IL-6 (interleukin 6) mutant mice failed to produce T17 immunity in response to NE adjuvant. Mice deficient in TLR2 and TLR4 (Toll-like receptors 2 and 4) had a diminished IL-17 response. Our data indicate that nasal mucosal immunization with NE adjuvant produces T1 and T17 immunity; that this process requires IL-6, CD40, and at least one of the CD80/CD86 molecules; and that the induction of TH17 is enhanced by the presence of TLR2 and TLR4 receptors. This unique approach to vaccination may have a significant role in protection against mucosal and intracellular pathogens.