Lundin, Rosenberg, and Woodall all comment, rightly, that a program of global epidemiological surveillance should be justified first on the basis of its benefits to global public health, and only secondarily on the basis of its contribution to weapons control. I agree, but I present my proposal in the context of weapons control because it is in that context that I became convinced of the necessity of such a program. My intent was to determine how one would recognize, and thereby deter, the clandestine use of biological agents (which I believe to be the most likely form of use). This analysis led to the conclusion that a global program of epidemiological surveillance is essential for biological weapons control.