The Working Group was composed of experienced members from the science community and senior practitioners from the fire service, law enforcement, emergency medical, hazardous materials, and responder-education fields. The Working Group proposes a five-step process that can be completed in a few minutes with the use of inexpensive equipment and materials. The test is designed to assess in the field particle size, solubility, pH, and protein content, all of which are variables that can characterize the nature of a dry material found in a suspect letter or parcel. The equipment required includes a small clean vial with leak-proof cap (a 3 ml glass or borosilicate vial can be purchased at a medical or laboratory supply store for less than $2.00); pH paper test strips; protein test strips; a small disposable spatula or scoop; distilled water; and a magnifying glass (10 or 20x). The five steps described -- sample, shake, water, pH test, protein test -- can provide the typical American community an acceptable rule-out capability at very low cost. Responder units should have the equipment necessary for and the training to conduct the field test described. 3 tables and 3 references