In this paper we demonstrate the ability of inelastic (Raman) light scattering to probe polymerization transitions. We show that after proper treatment-that is, separating isotropic and anisotropic contributions and employing the reduced representation which removes the thermal population effect of vibrational energy levels-the Raman data can be used as an accurate quantitative indicator of monomer<---->polymer transitions. In particular, we have applied this method to study the thermoreversible polymerization transition of liquid sulfur up to 300 degreesC. Raman spectra obtained from rapidly quenched samples over a broad low-temperature range, from -180 degreesC to ambient temperature, revealed the fact that the equilibrium between monomers and polymers in the solid amorphous state is precarious; thus quench-and-dissolution methods employed to determine the polymer content of the liquid are not accurate. Our data are compared with existing data obtained via quench-and-dissolution techniques showing considerable dissimilarities above 250 degreesC. Our experimental data seem to conform better to the equilibrium polymerization transition theories than previously reported data especially in view of the lack of a high-temperature plateau value in the extent of polymerization, although complete agreement between experiments and theory is still missing. Finally, the width of the Raman peak assigned to polymeric sulfur vibrations has been used as a rough indicator of the size distribution of sulfur chains. (C) 2003 American Institute of Physics.