Cells of most vertabrate species contain proteins, such as fibronectin, whose function is to facilitate cell adhesion to extracellular substrate surfaces or to other appropriate cells. Assays reported in the literature are available to quantitate these proteins. I obtained instruction in these assays from Yamada's group, and tested various parameters of the assay procedure. I determined the optimum level of fibronectin required to coat the plastic surface of the assay wells, and the optimum incubation time required for the assay. The effect of certain fibronectin-derived peptides was tested on fibronectin-mediated BHK cell adhesion to the surface of the plastic assay wells. From such assays as these, Yamada has ranked the various peptides in order of their relative activities in promoting cell adhesion to the fibronectin and other adhesion proteins. I have also focussed on work with molecular models, to construct some of these peptides. Data for most of the bond angles were found in the literature. These models should help determine crucial structural feature involved in cell binding and adhesion.