In a recently completed test program at the U.S. EPA Incineration Research Facility (IRF), 10 prototype or developing continuous emission monitors (CEMs) for measuring trace metal or trace organic species concentrations were tested. Of the 10 CEMs tested, four measured concentrations of several specific volatile organic compounds, one measured total particulate-bound polynuclear aromatic hydrocarbon concentrations, two measured concentrations of up to 14 trace metals, and three measured mercury concentrations. Four series of tests were performed, each simultaneously testing up to three monitors measuring the same or similar analyte type. All measurements were taken in the wet scrubber exit flue gas from the pilot-scale rotary kiln incineration system at the IRF. The test program results clearly showed the prototype nature of most approaches tested, and the clear need for further development.