Stable isotopic analysis--particularly compound specific stable carbon isotopic analysis--is being increasingly investigated and applied as a tool to investigate and monitor the sources and fates of contaminant compounds in the environment. Results of an increasing number of studies indicate that stable isotopic analysis is a promising tool in environmental chemistry. This paper discusses reported results and presents a case study of stable carbon isotopic analysis of volatile organic groundwater contaminants to illustrate the present abilities and limitations of the application of stable isotopic analysis to environmental contaminants. Though this paper focuses on stable carbon isotopic analysis of volatile organic compounds, the principles discussed herein are relevant to all applications of isotopic analysis as an environmental forensic tool.