Vaccines optimize the presentation of an immunogen to the immune system, oftentimes enhancing or replacing the natural activators of antigen presenting cells in order to promote the delivery and the response of T and B lymphocytes to the immunogen. The purpose of this series is to describe new technologies which allow vaccine design, based on our understanding of the immune response, using different approaches to immune peptide enhancement of peptide based vaccines. In this introduction to the series entitled, "Immune Peptide Enhancement of Peptide Based Vaccines", some of the immunological concepts relevant to vaccine design are presented.