The 23 articles written for the 2008 edition of the respected annual series summarize recent advances in understanding lymphocyte development and differentiation, the regulation of immune response, cytokines, phagocytosis and inflammation, autoimmunity, and the immunology of infectious diseases and vaccines. The contributors review research findings on protein tyrosine phosphatases, interleukin-21, class switch recombination, thymus organogenesis, somatic hypermutation, and T follicular helper cells. Other topics include conserved amino acids that control TCR-MHC interaction, migration of dendritic cell subsets, the actin cytoskeleton in T cell activation, and granzyme pathways of programmed cell death.