Immunology has progressed in spectacular fashion in the last four decades. Studies of the response to infectious agents, transplanted organs and tumours (and the potential to manipulate that response), and the study of the immune system as a model system in molecular cell biology have yielded dramatic advances in our understanding of the mechanisms of immunity. The field has attracted a continuous stream of the brightest theoretical and experimental scientists for over forty years. This book conveys the philosophies and approaches of sixteen of the most successful of these scientists in the form of a series of narratives that describe the circumstances that led to a major discovery in immunology. Contributors not only recall an exciting period of research that helped shape modern immunology, but set it in the personal context of place and time. Jacques Miller, for example, describes the discovery of the function of the thymus, Rolf Zinkernagel explains how experiments on viral immunity led to the discovery of MHC restriction and Susumu Tonegawa provides an account of how antibody gene structure was defined. Medically-important discoveries include descriptions of early studies of autoimmunity by Noel Rose and of tumour immunology by George and Eva Klein. Far from being a collection of disinterested, historical accounts, this volume comprises a series of passionately biographical, personal essays that provide an unusually intimate insight into the scientific process. This book will be essential, and fascinating, reading for all those with an interest in immunology, and in the life sciences in general. For students and teachers, this will provide the background necessary for a true understanding of immunology, and to place subsequent discoveries in perspective.