Large macromolecules with hydrophobic backbones are known to assemble at the interface between immiscible liquids. This assembly is often unpredictable because sol. the subtle interplay among hydrophobic interactions, hydrophilic solvation, structural constraints, and the thermodynamics of adsorption. In these studies, we employ vibrational sum frequency spectroscopy and interfacial tension measurements to study the assembly of a simple polyelectrolyte, poly(methacrylic acid), as it assembles at the interface between two immiscible liquids, specifically, carbon tetrachloride and water. By adjusting,: the polyelectrolyte charge through pH studies and the polymer size through molecular weight studies, we demonstrate that charge accumulation in segments of the :polymer chain's is a Critical :factor in macromolecular interfacial adsorption and desorption The results have implications for related charged macromolecules whose ability to assemble between two immiscible fluid media is essential for many biological processes, water remediation: efforts, and enhanced oil recovery.