We studied by differential scanning calorimetry (DSC) the influence of three tertiary amines used as promoters on the curing kinetics of unsaturated polyester resins catalyzed with an organic peroxide. The kinetic study was made by means of the analysis of isothermal experiments and we used a kinetic model that does not presuppose knowledge of the experimental rate equation f(alpha), which relates the reaction rate dalpha/dt at constant temperature with the degree of conversion alpha through a rate constant k according to dalpha/dt = kf(alpha). It is thus possible to predict the time, temperature, and degree of curing without needing to know f(alpha). This model makes a linear relation between the logarithm of time needed to reach a given degree of conversion with the inverse of the curing temperature according to the expression In t = A + E/RT for a constant a, where A is a constant, R is the universal gas constant, and E the activation energy. The proposed model has been used to calculate the activation energies for each degree of conversion according to the type and amount of promoter used. From the relation between the time and the curing temperature for a given conversion, it is possible to predict values of curing time for different temperatures. We thus simulated curing kinetics by using the proposed model and compared them with those obtained experimentally by DSC.