A unique light scattering photometer has been developed for continuous measurement of the complete angular spectrum of light scattered by dynamically changing systems. Although primarily designed for work with biological particles such as large viruses, subcellular organelles, and bacteria, it can be used to study polymerization and depolymerization of macromolecules, synthetic polymers, etc. The instrument has been applied to the direct measurement of the diameter of phospholipid vesicles and micelles in chromatographic column effluents and to the dynamics of polymerization of microtubular protein and osmotic lysis of chromaffin of granules.