Avian influenza virus (AIV) H9N2 subtype is a low pathogenic influenza virus that commonly infects poultry in certain parts of the world. Inactivated AIV vaccines can be used to decrease infection. Our objective was study the immunogenicity of inactivated H9N2 AIV vaccines in chickens. To this end, we performed studies that examined: 1) the combination of Toll-like receptor (TLR) ligands as adjuvants, 2) the inactivation method used to produce H9N2 AIV vaccines, and 3) the administration of inactivated H9N2 AIV vaccines in ovo to chicken embryos. We observed that the TLR21 ligand, CpG ODN 2007, is an effective vaccine adjuvant for inactivated H9N2 AIV intramuscular chicken vaccines, beta-propiolactone inactivated H9N2 AIV leads to increased immune responses in chickens, and in ovo vaccination with inactivated H9N2 AIV vaccines is plausible. In conclusion, this thesis provides information on various factors which impact the immunogenicity of inactivated H9N2 AIV vaccines in chickens.