A coordinated approach using biochemical and immunological tools has given us a better understanding of the structure of the eukaryotic surface membrane. From such studies has emerged the fluid mosaic model of membrane structure and this volume contains a collection of articles written by noted workers in this field. A major emphasis in this area of research concerns the changes brought about on virus-induced and carcinogen-induced tumor cells. The first chapter comes from a laboratory that was one of the first to visualize the distribution of transplantation antigens on cell membrane surfaces. Various methods are described for visualizing these antigens by electron microscopy. Davis and his colleagues then proceed to show how the antibody-induced redistribution of antigenic macromolecules led to the formulation of the fluid mosaic model. From Hakomori's laboratory comes a methodological paper describing a novel method of labeling the carbohydrate portions of the membrane glycoproteins that are exposed on the outer surfaces of cells. The two chapters reviewing the changes found on carcinogen-induced and virus-induced malignant cells complete the survey of the structures associated with surface mem­ branes. Thanks are due to Mrs. Carol Garafolo who helped immeasurably with the preparation of the index for this volume.