Monoclonal antibodies (mAbs) are indispensable tools for the study, diagnosis and treatment of pathological conditions. The major purpose of the Epitope Recognition Immunoreagent Core (ERIC) is to assist RDCC investigators with the development, characterization and production of monoclonal reagents relevant to the study of rheumatic diseases (RDs). The ERIC has evolved from expansion and diversification of the Arthritis and Musculoskeletal Center's Hybridoma Core Facility which has been in operation since 1981. In addition to supplying traditional hybridoma services, the ERIC provides RDCC investigators with novel approaches for mAb development as well as expertise in immunoassay design, epitope characterization, and phage display technology. The core provides standard hybridoma services such as: procurement and housing of pathogen-free rodents, design and coupling of peptide immunogens, planning and implementation of immunization protocols, immunoassay design, sera testing, performance effusions and screening assays, single cell cloning, isotyping and large-scale production and purification of mAbs. At present, the core maintains a freezer inventory of approximately 10,000 vials which includes hybridomas produced in house and also commonly requested hybridoma lines obtained from American Type Tissue Collection (ATCC) or deposited by individual investigators. By virtue of the ERIC's 25 year association with UAB's Arthritis and Musculoskeletal Disease Center, many of hybridomas stored in the ERIC are related to the study of RDs. A panel of commonly requested monoclonal reagents is made available to RDCC investigators through the ERIC including;anti-tag mAbs (i.e. MYC, HA, HIS, GST, GFP, FLAG), anti-mouse and human CD mAbs and rat and mouse isotype-matched control mAbs. Another important function of the ERIC is to provide RDCC investigators with novel, state-of-the-art methodologies that are not readily available from other sources. Antibody phage display technology has been available through the core since 2000 and more recently peptide phage display was incorporated. Another specialized technology that is provided by the core is avian monoclonal antibody development. Avian mAb technology provides an alternative strategy for deriving high affinity mAbs to highly conserved mammalian proteins.