The chemistry driving dimethyl sulfide (DMS) oxidation and subsequent sulfate particle formation in the atmosphere is poorly constrained. We oxidized two related compounds (dimethyl sulfoxide and dimethyl disulfide) in the laboratory under varied NO_x conditions and measured the gas- and particle-phase products. These results demonstrate that both the OH addition and OH abstraction pathways for DMS oxidation contribute to particle formation via mechanisms that do not involve the SO₂ intermediate.