NACE RP 01-69 and Canadian Recommended Practice OCC-1 caution against using polarized potentials less negative than -850 or -770 mV, respectively, on underground pipelines where other conditions may be conducive to external stress corrosion cracking (SCC). The cautionary statement is based on research which suggests that application of the 100-mV polarization criterion can promote SCC, but this research has not been developed to the point of being able to provide guidance to pipeline operators. The objective of the research summarized in this paper was to define pipeline conditions where use of the 100-mV polarization criterion may be conducive to possible SCC problems.