The polymerization of a phenolic resole resin, used as a matrix for glass-fiber-reinforced composite materials, was studied using differential scanning calorimetry (DSC), and a kinetic model of the complex reactive process was developed. Two distinguishable reaction peaks were obtained in the dynamic DSC thermograms and were assigned to two independent cure reactions characterized by different activation energies. The kinetic analysis, performed by regression analysis on several DSC scans obtained at different heating rates, led to the determination of kinetic constants, activation energies and reaction orders for the two different kinetic equations. Both equations were integrated in a general model of the cure process through the inclusion of a weighting factor representing the fraction of heat developed in each reaction. Good agreement between experimental and modeling results was obtained.