With the identification of ever more protein components associated with cellular adhesion sites, the nature of the mechanisms underlying assembly and maintenance of these important cellular structures was in danger of becoming completely intangible. However, new information on how the interaction between the different proteins can be regulated is beginning to shed more light on this problem. In particular, recent biochemical and electron microscopic data on the overall structure and function of vinculin, one of the key structural proteins involved in cellular adhesion, leads to a novel model for the regulation of cellular adhesion.