Experimental data and model results are presented for the effects of m-xylene on aromatic species and soot in a nitrogen-diluted ethylene flame over a range of pressures from 1 to 5 atm. The experimental approach was designed to investigate the effects of m-xylene as a perturbation to a base flame by keeping the amount of carbon added as m-xylene to 5% or less. The experimental results indicate that the maximum soot levels and those of small (1 or 2 rings) and large (3 or more ring) aromatic species are roughly first order with respect to the amount of m-xylene added. A chemical kinetic model was formulated, integrated into a 2-D modeling code, and used to simulate the effects of m-xylene addition and pressure on aromatic species and soot. The modeling results capture the general trends in concentration of soot and small aromatics as m-xylene concentration and pressure are varied. However, the model under-predicts the effect of m-xylene concentration and pressure on soot compared to the experimental results. (C) 2012 The Combustion Institute. Published by Elsevier Inc. All rights reserved.