IEST RP-CC031.3 describes a method for characterizing organic compounds outgassed from materials or components exposed to air or gases in cleanrooms and other controlled environments. New to the latest revision is a 4-page table listing materials of construction found in cleanrooms, generic classes of organic compounds known to outgas from these materials, and examples of problems caused by certain organic compounds. The RP is relevant to industries that may experience adverse production yields as a result of gaseous organic contamination. This document provides both a semi-quantitative determination and a qualitative indentification of a large range of compounds detectable by dynamic headspace gas chromatography-mass spectrometry (GC-MS). Supersedes previous editions of IEST-RP-CC031.