A new Static Light Scattering (SLS) method for measuring the Second Virial Coefficient (A2) uses the DAWN and miniDAWN light scattering and Optilab rEX refractometer instruments. The Second Virial coefficient (A2) is a thermodynamic parameter used to characterize equilibrium solutions of weak non-specific protein-solvent interactions and is essential to understand a wide array of processes, such as stabilization of therapeutic protein formulations, purification of protein mixtures and crystallization of proteins. Both self and cross-association can be quantified by Virial coefficients. A2 values are dependent on the protein and its solvent as well as temperature, salinity, pH and presence of chemical excipients. Results showing positive A2 point to repulsive intermolecular interaction, while negative A2 demonstrates attractive intermolecular interaction. The new method allows for rapid determination of buffer conditions required to tune A2 to a particular value. For example to develop a formulation buffer, a positive A2 is required, whereas for crystallization, a small negative value is desirable. With the new method, many conditions can be tried and characterized until an optimal buffer composition is found.