The products of the gas-phase reactions of styrene and 2-vinylpyridine with O3, OH radicals, and NO3 radicals have been studied at room temperature and atmospheric pressure of air. The reaction kinetics were also measured for those reactions not previously examined. The major products of the ozone reaction with styrene were formaldehyde and benzaldehyde, each with yields of approximately 40%. The OH radical reaction with styrene also formed benzaldehyde and formaldehyde with yields of 63 +/- 6% and 72 +/- 7%, respectively. The reaction of styrene with the NO3 radical formed equal, minor yields (ca. 11%) of HCHO and C6H5CHO, with the remaining unidentified products consisting of transient and stable species which contain ONO2, OONO2, and C=O groups. The 2-vinylpyridine reaction with ozone produces 2-pyridinecarboxaldehyde and formaldehyde, with respective yields of 80 +/- 9% and 34 +/- 5%. 2-Pyridinecarboxaldehyde was also the major product of the OH radical reaction with 2-vinylpyridine, with a yield of 78 +/- 14%.