Aromatic hydrocarbon formation and oxidation is discussed in the context of detailed chemical kinetic modeling of cyclopentene flames and methyl-cyclopentadiene pyrolysis in a shock tube. The main objective is to explore the relative roles of cyclopentadienyl-and phenyl radical-based sequences leading to the formation of naphthalene and indene in a system featuring a high cyclopentadienyl to phenyl radical ratio. The work is also motivated by a desire to explore the importance of possible linkages between cyclopentadiene/benzene and indene/naphthalene through CH 3 or 1 CH 2 / 3 CH 2 addition reactions. Naphthalene formation is considered in the context of a number of tentative detailed sequences that include C 8 H 5 โซืโฌ C 2 H 2 , C 6 H 5 โซืโฌ C 4 H 4 , and C 7 H 7 โซืโฌ C 3 H 3 routes as well as initiation via C 5 H 5 โซืโฌ C 5 H 5 . It is shown that that a fast cyclopentadienyl-based recombination route is not consistent with experimentally determined naphthalene concentrations under the conditions considered. The study lends support to the suggestion that the addition of CH 3 to C 5 H 5 is a viable path for benzene formation. Attention is also placed on paths leading to different isomeric C 9 H 8 structures, and it is shown that steps such as C 6 H 5 โซืโฌ C 3 H 3 have the potential to explain indene formation with good quantitative accuracy. The study further suggests that an important route to naphthalene formation is initiated via acetylene addition to the ethenylphenyl radical.