This report describes the experimental design and the results of the validation study for two analytical methods to detect polychlorinated byphenyls in oil. The methods analyzed for four PCB Aroclors (1016, 1242, 1254, and 1260), 2-chlorobiphenyl, and decachlorobiphenyl. The first method consisted of diluting the oil in hexane and analyzing by gas chromatography using an electrolytic conductivity detector in the separating with sulfuric acid extraction or with column chromatography, and analyzing by gas chromatography using an electron capture detector. Four oils types were used in this study: capacitor fluid, hydraulic fluid, transformer oil, and waste oil. Each oil was spiked at six concentration levels with comprised three Youden pairs. Capacitor fluid was spiked with Aroclor 1016, hydraulic fluid with Aroclor 1242 and 2-chlorobiphenyl, transformer oil with Aroclor 1260 and decachlorobiphenyl, and waste oil with Aroclor 1254. Statistical analyses and conclusions presented in this report are based on analytical data obtained by eighteen participating laboratories and two volunteer laboratories. The two methods are assessed quantitatively with respect to the precision and accuracy that can be expected for each. In addition, various aspects of the methods are discussed, including such topics as method detection limits, sample stability interferences, and qualitative assessment of the methods based upon comments by the participating laboratories.