This paper critiques available environmental engineering demographics and presents estimated populations for students, faculty, and practitioners in the USA. Limited environmental engineering demographics exist because most data are collected for named environmental engineering degrees and named environmental engineering departments. American Association of Engineering Societies Engineering Workforce Commission (http://www.asee.org, 2004) has the best student data with comprehensive participation, and annual reports. Estimates for 2004 graduates suggest approximately 496 bachelors, 590 masters, and 119 doctorate degrees. However, many academic programs do not offer undergraduate environmental engineering degrees. Based on civil engineering student populations, the authors suggest that 1,245 undergraduates who will practice environmental engineering received engineering degrees (regardless of title) in 2004. American Society for Engineering Education is the main source for demographics for faculty; however, only members in stand-alone departments are counted, and the data were first reported in 2003. 2003 estimates are just over 100; however, the authors suggest that there are approximately 1,100 environmental engineering faculty based on Association of Environmental Engineering and Science Professors membership. For environmental engineering practitioners, the Bureau of Labor Statistics (BLS) provides a reasonable, 2003 lower end estimate (based on statistical samples) of 45,500. Based on population, the authors conclude that environmental engineering is midsized relative to other engineering disciplines. Recognized sources of demographics for engineers should be encouraged to report environmental engineering as a distinct category. Also, relevant organizations should work with EWC and ASEE to determine better estimation methods for those environmental engineering students, faculty, and resources currently aggregated with other disciplines.