A laboratory-scale lagoon was constructed and loaded with swine wastes while the temperature was varied from 30 to 1°C on a 120-day cycle. The lagoon was shown to generate particles in the 0.5–3-μm range. The number of particles ranged from 880 to 16 000 1 −1 and was least when the temperature was low. The lagoon liquid was analyzed for volatile odor compounds during the temperature cycle. In general, the same volatile peaks were found throughout the lagoon cycle, but the volatiles reached maximum values as the temperature rose above 15°C. A number of the odor volatiles were identified by gas chromatography-mass spectrometry, but the analysis was complicated by the presence of large amounts of volatile hydrocarbons in the swine wastes that obscured the odorous compounds. A synthetic medium inoculated with lagoon organisms and incubated anaerobically was capable of generating typical lagoon odors. Amino acids were the primary precursors of odor compounds, and it was possible to demonstrate the conversion of a number of amino acids to specific odorous compounds.