a new method is presented for characterizing the associative properties of a solution of macromolecules at high concentration . sample aliquots spanning a range of concentrations are injected sequentially into a light scattering photometer . equilibrium association constants and association stoichiometry are derived from an analysis of the angular and concentration dependence of the scattering signals . thermodynamic nonideality , which becomes important at high concentrations , is dealt with in the analysis in a simplified manner which is applicable to multiple associated species .