This lecture traces the evolution of hematopathology from the time of Thomas Hodgkin to the modern era of hybridoma antibodies, immunophenotyping, and molecular biology. It highlights the early concepts of Ludwig Aschoff and his school based on the observations of Metchnikoff, Ehrlich, and Maximow and the changes in concepts and terminology that have occurred in the ensuing 80 yr. The ongoing controversy on terminology and classifications of the malignant lymphomas from their first descriptions by Rudolf Virchow, Hans Kundrat, and Theodore Billroth is reviewed with reference to the development of the Working Formulation of Non-Hodgkin's Lymphomas for Clinical Usage and other classifications that are currently in vogue. Special attention is paid to the remarkable insight showed by Dorothy Reed in her morphologic descriptions of Hodgkin's disease, her thoughtful discussion on the nature of this disorder, and the conformation of her proposals inherent in the subsequent classification of Lukes and Butler. Acknowledgement is given to the remarkable discovery of Köhler and Milstein resulting in the advent of monoclonal antibodies that have revolutionized the field of hematopathology; to the many immunopathologists who have been responsible for the production of more than 1100 monoclonal antibodies comprising 78 clusters of differentiation; and to many of the leading molecular biologists who have (in the words of Berard) "helped to transform hematopathology from a difficult morphologic exercise into a functionally oriented biologic science."