This talk will discuss the adsorption and displacement of fibrinogen at the silica/aqueous interface. It has been known since Leo Vroman's original studies in 1969 that fibrinogen is one of the first proteins to adsorb from human plasma on oxide surfaces, but it is ultimately displaced by other smaller and less abundant species in solution. We have employed a combination of vibrational sum frequency spectroscopy (VSFS), atomic force microscopy, immunoassays, and kinetic studies to unravel the molecular level details of the mechanism for this process. The results reveal that lysine and arginine residues on the protein's alpha-C domains interact with the surface via weak electrostatic binding. The rest of the protein can only make stronger hydrogen bonding and hydrophobic contacts once these domains have been displaced. In particular, the VSFS data give direct evidence for alignment of arginine and lysine residues with the surface in the protein's most displaceable configuration.