ABSTRACT: The structure of molecules adsorbed at the solid-liquid interface is critical to understanding the biocompatibility of materials, the design of biosensors, antimicrobial activity, and efficiency in chemical separations. Yet, despite these wide-spread applications, there is a paucity of techniques that are capable of characterizing surface-adsorbed molecules with sufficient selectivity and structural sensitivity. Furthermore, progress in unravelling molecular-level processes in these areas is equally reliant on understanding how water interacts with the adsorbates before, during, and after the adsorption process. Our group has been working on combined optical probe and molecular modeling approaches to provide a description of solvent and solute structure at solid-liquid interfaces. A unique aspect of our experimental effort is the ability to resolve the polarity of chemical bonds, distinguishing functional groups pointing up or down at the surface in an absolute sense. My talk will provide a few recent examples from each of these closely interlinked areas.