This issue of Veterinary Clinics:: Food Animal Practice, guest edited by Dr. Christopher Chase in collaboration with Consulting Editor Dr. Robert Smith, focuses on Ruminant Immunology. Article topics include:: Herd immunity:: an epidemiologists view; Genetics of immunoresponsive and correlates of immunity; Microbiome and immunity:: an evolving field; Vaccine administration dos and donts (endotoxin stacking; delayed MLV); Mycoplasma bovis:: interations with the immune system and failure to generate an immune response; Nutriceuticals and their effect on immune response; Adjuvants; Immunology of maximizing passive transfer; Mucosal immunity and common mucosal response; Vaccinating in the face of maternal immunity; and Gamma Delta T cells in ruminants:: their role, function, and importance.