The molecules on the cell surface that mediate inflammatory interactions between endothelial cells and leukocytes and of leukocytes with one another have been isolated and their fine structure elucidated. Early studies clearly indicated that the interactions mediated by these proteins are involved in the pathogenesis of rheumatoid arthritis. This article is a review of work published over the past year that has confirmed and expanded the role of adhesive proteins on vascular endothelium, leukocytes, and other synovial cells in the pathogenesis of rheumatoid arthritis. Moreover, the results of recent studies have suggested novel strategies for the development of agents for the treatment of rheumatoid arthritis.