This volume is a practical biochemical guide to the Enzyme-Linked Immunosorbent Assay (ELISA), used to detect a target substance in a liquid sample. The ELISA is an important and widely used diagnostic tool in medicine, animal health, botany and quality assurance processes in food and beverage production. An introductory chapter orients the reader on the basic structure and function of immunoglobulins and their fragments while subsequent chapters outline the methodology to generate monoclonal antibodies using hybridoma technology and the general methods used to purify antibodies. Multiple chapters demonstrate how to creatively use the properties of the antibody to identify, localize and quantify target analytes to answer questions and resolve problems. The reader will learn how to use a variety of immunoassay strategies, reporters and detection systems that will undoubtedly facilitate their efforts to gain answers to their own questions. Written in the successful Methods in Molecular Biology series format, chapters include introductions to their respective topics, lists of the necessary materials and reagents, step-by-step, readily reproducible protocols and notes on troubleshooting and avoiding known pitfalls. Authoritative and easily accessible, ELISA: Methods and Protocols seeks to provide both professionals and novices with the technical information necessary for the reader to successfully use the immunoassay as part of the discovery process.