SYNOPSISThe techniques of dynamic mechanical thermal analysis (DMTA) and differential scanning calorimetry (DSC) were used to examine the effects of the addition of various fillers and extenders (clay, pecan shell flour, and wheat flour) on the curing mechanism of a phenolformaldehyde resol. The DMTA results indicated that the curing process was unaffected by any of the additives. The DSC thermograms showed a single exothermic peak that was not influenced to a great extent by the fillers or extenders. Comparison of viscosity measurements and gel time determinations showed slight differences in the physical properties of the uncured resins.