Macromolecular assembly at the interface between water and a hydrophobic surface underlies some of the most important biological and environmental processes on the planet. Important model systems for understanding this assembly at such interfaces are polyelectrolytes that have hydrophilic units interspersed along a hydrophobic polymer backbone, similar to many biological macromolecules. This feature article provides recent advances in the molecular factors that contribute to the adsorption and assembly of carboxylic acid-containing polyelectrolytes at the carbon tetrachloride-water interface, a model system for an oil-water interface. Using vibrational sum frequency spectroscopy and interfacial tension techniques, these unique set of studies presented herein identify the factors that dictate whether or not polyelectrolytes will adsorb to the oil-water interface, and also describe the specifics of the adsorption process that depend upon factors such as polymer size, charge density, hydrophobicity, conformation and the effect of metal ion electrostatics and bonding.