Advances in the life sciences and in enabling technologies affect the operations of both the Chemical Weapons Convention and the Biological and Toxin Weapons Convention. Both treaty regimes have developed mechanisms to review scientific and technological advances in order to ensure that their future implementation will not be negatively affected by such developments. These reviews also identify opportunities where new scientific knowledge and technology can help enhancing the effectiveness of the treaty regimes, or improve protections against CB weapons. This paper reviews experiences with both formal and informal mechanisms to provide effective and meaningful science advice to the States Parties of the two conventions, and in the case of the CWC also the international agency implementing it (the OPCW). These mechanisms include, for example, the provision of scientific advice by government scientists, in the CWC case by the Scientific Advisory Board of the OPCW, and independent advice received from international science unions, the Inter-Academy Panel, the International Council for Science and other international scientific institutions, as well as industry associations. The paper concludes that independent science advice is important for the proper functioning of the two conventions, and that dialogue between the science, technology and industry community on the one hand, and the arms control and security community on the other, is needed if the conventions are to be implemented in depth, and made to adapt to new requirements emanating from advances in the life sciences.