The fourth installment of The Year in Immunology series features reviews of novel approaches in the investigation of immunoregulatory mechanisms. Topics surveyed include cutting-edge molecular studies and treatment advances for systemic lupus erythmatosus and multiple sclerosis, the genetic regulation of lymphocytes and T cells, and new models of immunosenescence. NOTE: Annals volumes are available for sale as individual books or as a journal. For information on institutional journal subscriptions, please visit http://ordering.onlinelibrary.wiley.com/subs.asp?ref=1749-6632&doi=10.1111/(ISSN)1749-6632. ACADEMY MEMBERS: Please contact the New York Academy of Sciences directly to place your order (www.nyas.org). Members of the New York Academy of Science receive full-text access to Annals online and discounts on print volumes. Please visit http://www.nyas.org/MemberCenter/Join.aspx for more information about becoming a member.