Epoxy-anhydride cure has been studied by differential scanning calorimetry under nonisothermal conditions. The isoconversional method of kinetic analysis yields a dependence of the effective activation energy on the extent of conversion (alpha) that increases from approximate to 20 to 70 kJ.mol(-1) with increasing alpha. The occurrence of the dependence suggests a mechanism of competing reactions that are found to be the processes of initiation and propagation of the polymer chain.