The RAMP Anthrax Test Cartridge for detecting Bacillus anthracis was validated for use in the field for detection of B. anthracis spores in visible powder residues on 7 nonporous environmental surfaces. Six teams of trained first responders and civil support personnel in Class C personal protective equipment sampled visible powder residues on plastic, stainless steel, ceramic tile, wood, rubber, sealed concrete, and food-grade painted wood and analyzed the samples on the RAMP Anthrax Test System. The accuracy for each surface was at least 97% and the overall average was 98.8%. The overall average false-positive rate was 1.79% and false-negative rate was 1.07% for all surfaces. There were no significant differences between surfaces or between spore levels.