The Biological and Toxin Weapons Convention (BWC) member states have looked to the verification provisions of the Chemical Weapons Convention (CWC) for guidance in crafting a compliance monitoring protocol. Both treaties require the elimination of existing stocks of warfare agents and prohibit their acquisition in the future. Both also address the challenge of distinguishing the production of chemical or biological weapons from the peaceful applications of industrial chemistry and biology. Some countries favor adopting the basic elements of the CWC verification regime in the BWC compliance protocol based on these similarities. Important differences between chemical and biological weapons limit the applicability of CWC verification measures to the BWC. The first difference is that certain microbial and toxin agents are highly potent per unit weight measure meaning a militarily significant quantity is measured in kilograms, rather the with tons for chemical nerve agents. Second, production of a chemical arsenal requires a large industrial plant, whereas a stockpile of biological or toxin agents could be produced to order in a pilot-scale facility over a period of weeks. The threshold for militarily significant cheating, or “treaty breakout,” is considerably lower for the BWC than for the CWC. The ambiguities between offensive and defensive research on infectious agents make it more difficult to distinguish between prohibited and permitted activities at dual-capable biological facilities, therefore assessing intent is as important as physical evidence in determining BWC compliance. The wholesale transplant of measures from the CWC verification regime to the BWC protocol is not appropriate, however, several elements of the verification regime are relevant to the BWC compliance protocol. These elements include establishing a set of mutually reinforcing measures ranging from facility declarations to on-site inspections, and adopting a CWC-like system to reward states that comply with the treaty while punishing those that fail to adhere to its provisions. 2 tables, 60 footnotes