Book excerpt: Developing Costimulatory Molecules for Immunotherapy of Diseases highlights the novel concept of reverse costimulation and how it can be effectively exploited to develop immunotherapy using either humanized antibodies against CD80, CD86, and other costimulatory molecules or CD28 fusinogenic proteins in the treatment of diseases, including allergies, asthma, rheumatoid arthritis, multiple sclerosis, lupus nephritis, severe psoriasis, vulgaris tuberculosis, thopoid, transplantation therapeutic, cancer, and inflammation. The text aims to provide the latest information on the complex roles and interactions within the CD28 and B7 costimulatory families, with the hope that targeting these families will yield new therapies for the treatment of inflammation, autoimmunity, transplantation, cancer, and other infectious diseases. - Highlights the novel concept of reverse costimulation and how it can be effectively exploited to develop immunotherapy - Provides the latest information on the complex roles and interactions within the CD28 and B7 costimulatory families - Targets new therapies for the treatment of inflammation, autoimmunity, transplantation, cancer, and other infectious diseases