As they appeared in the first edition of this reference, some of the detailed descriptions of graft-vs.-host disease (GVDH) were impenetrable to readers who lacked specialty training in immunology; a field that has exploded in the last decade. To ameliorate the problem, the new edition includes an introductory series of chapters that review aspects of immunobiology necessary to the understanding of GVDH. Subsequent sections contain chapters on GVDH pathophysiology; target organs, and network activation and dysregulation; and prevention and treatment--current strategies and alternative approaches.