Results are reported for important developments in modeling the combustion and oxidation kinetics of aromatic compounds, using theoretical techniques in computational chemistry and statistical rate theory. Aromatic hydrocarbons are important fuel components and atmospheric pollutants, and are also involved in the formation of unwanted soot and PCDD/Fs. First, unimolecular and bimolecular reactions of the resonantly-stabilized benzyl radical are considered. Novel, low-energy pathways are presented for the thermal decomposition of benzyl to fulvenallene + H and to the cyclopentadienyl radical + acetylene. Modeling results are in good agreement with the measured rate of benzyl decomposition. The proposed reactions should be important at higher temperatures, but at lower temperatures bimolecular association reactions with radical species like HO₂ and OH are expected to dominate. The benzyl + HO₂ reaction process is modeled, and is shown to lead to benzoxyl + OH formation. Several rapid reaction pathways are available from the benzoxyl radical, to benzaldehyde + H, phenyl + CH₂O, and benzene + HCO. Finally, the reactions of substituted phenyl radicals with O₂(³P) and phenoxy radicals with O(³P) are considered. The results of this study provide a greater fundamental understanding of the reaction processes and products in aromatic combustion and oxidation, as well as offering improved input parameters for kinetic models.