The misuse of Bacillus anthracis as a bioweapon continues to be a serious concern. Medical personnel and researchers are served well if appropriate non-pathogenic anthrax simulants can be used as countermeasures in preparative planning. While there are several accepted simulants of B. anthracis, the addition of another model organism would be beneficial. This investigation was undertaken to evaluate the suitability of B. pumilus as a simulant for B. anthracis. All organisms were grown on AK Agar #2 to foster sporulation. Optimum conditions for spore formation were determined for B. pumilus as well as for currently used anthrax surrogates B. atrophaeus and B. thuringiensis. Spore dimensions were determined by scanning electron microscopy. Comparative antibody binding studies using commercially available anti-Bacillus antisera were completed with the simulants as well as with a negative control organism, Clostridium sporogenes. We report that B. pumilus sporulated readily (2.9 × 10 10 viable spores per plate), had appropriate spore size (1.24 μm × 0.59 μm) and reactivity with anti-Bacillus antibodies. The characteristics of B. pumilus determined in this study suggest this organism represents a novel, suitable model for B. anthracis.