Systemic lupus erythematosus (SLE) in humans is characterized by inflammatory lesions in skin, joints, kidneys, the central nervous system (CNS), and elsewhere. The clinical manifestations are accompanied by autoantibodies to diverse self antigens, mainly but not exclusively derived from the cell nucleus. Autoantibodies are generally believed to cause most of the tissue damage, although direct injury via cell-mediated immunity is also important. This unit describes protocols for the quantitation of SLE-associated autoantibody levels in mouse serum: detection of anti-chromatin antibodies, detection of anti-single and anti-double-stranded DNA antibodies, and detection of rheumatoid factor. Support protocols for preparing chicken chromatin and dsDNA are included. Also included is an immunoglobulin allotype-specific adaptation of the basic autoantibody ELISA which is useful for measuring antibody production in chimeric animals. The unit includes an ELISPOT protocol for quantitating cells producing anti-chromatin, as well as a method for genotyping mice for the faslpr and fasLgld mutations.