The B7-CD28 family molecules are probably the most intensively studied receptor-ligand systems in the field of immulogy. This is evident from the explosive accumulation of literature, particularly in the last ten years. Recent years have witnessed rapid discoveries and characterization of new receptors and ligands in the family. These new pathways, although still in their infancy, have already brought much excitement to the field. However, until w, there has been single volume to cover this entire area. This book was created to bring together state-of-the-art information and critical thinking from the leading investigators. This book covers significant territory of this rapidly moving field from structural biology and biochemical signalling to immulogical functions and their potential applications in the treatment of human diseases. This is an excellent handbook and reference for immulogists, health professionals as well as medical students and graduate students in life science field.