Technical Abstract: Pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) was used to identify the major organic products produced by pyrolysis of three foundry sand resins: 1) Novolac and 2) phenolic urethane (PU) [both phenol-formaldehyde based resins], and 3) furan (furfuryl alcohol based resin). These resins are used in the metal casting industry as a 'sand binder' for making cores (used to produce cavities in molds) and molds for non-ferrous castings. During the casting process, the cores and molds are subjected to intense heat from the molten metal, which can reach temperatures as high as 1600oC. As a result, the organic resins undergo thermal decomposition and produce a number of complex organic compounds. In this study, the organics were tentatively identified by MS after pyrolysis of the resins at 750oC. The major thermal decomposition products from the Novolac, PU, and furan resins were derivatives of phenol, benzene, and furan, respectively. Compounds identified that are of potential environmental concern were benzene, toluene, phenol, o- and p-xylene, o- and m-cresol, and polycyclic aromatic hydrocarbons. Pyrolysis of the Novolac resin resulted in the generation of the most compounds of environmental concern. Because there is interest in beneficially using foundry molding sands in manufactured soils and other agricultural products, it is necessary that organic thermal decomposition products be identified to ensure environmental protection.