The polymer chain dynamics during polymerization process has been investigated by means of time-resolved dynamic light scattering (TRDLS) for linear (polystyrene; St) and branched polymer chains (polydivinylbenzene; DVB). Light scattering intensity and time-intensity correlation function (ICF) were obtained every 30 sec during bulk polymerization of St and DVB homopolymers. In the case of DVB, the ICF exhibited a power law behavior exclusively at the gelation point. On the other hand, polymerization of St resulted in formation of vitrified linear polystyrene. It was found that the TRDLS was able to detect the gelation threshold of the DVB system and vitrification of St. ©2000 American Institute of Physics.