We performed chamber experiments to measure the composition of the gas-phase reaction products of nitrate-radical-initiated oxidation of four monoterpenes. The total organic yield, effective oxygen-to-carbon ratio, and dimer-to-monomer ratio were correlated with the observed particle formation for the monoterpene systems with some exceptions. The Δ-carene system produced the most particles, followed by β-pinene, with the α-pinene and α-thujene systems producing no particles.