A kinetic model is developed and validated for the acid-catalyzed novolac phenol formaldehyde condensation reaction used to produce the precursor to epoxy novolac. Novolac is widely used in adhesives, structural laminates, coatings, and castings because of high thermal stability and chemical resistance. Fitting of a kinetic model to experimental data for the novolac polymerization showed that formaldehyde and methylol "Q" species do react with significantly different rates. However, in disagreement with previous literature modeling efforts, ortho and para sites react with similar rates, as do internal and external sites. This finding led to being able to account explicitly for the reactivity of available sites for each molecule, removing the need for site balances. This updated model reduced calculated error and allowed determination of the activation energy for novolac polymerization of 79.5 +/- 0.4 kJ/mol.