Porous polymer adsorbents have proven to be effective for collection and preconcentration of organic materials in air streams. As part of the Environmental Protection Agency, Industrial Environmental Research Laboratory-RTP Level 1 Procedure (1) for environmental assessment, XAD-2 resin, a polystyrene-divinylbenzene porous polymer, is used in an adsorbent trap for the collection of volatile organic species. The purpose of this study was to examine the stability of XAD-2 resin, particularly its thermal stability under simulated use conditions. While the bulk thermal stability of the resin may be good, introduction of contaminants on the milligram scale can be sufficient to give a large blank value in relation to the total collected material. In the present study, the magnitude of the thermally-induced blank was assessed primarily by measurement of the Total Chromatographable Organic (TCO) fraction of the resin extract. In addition, a gas chromatography/mass spectroscopy (GC/MS) study of several of the extracts was carried out to identify the components of the blank.