The way in which any international treaty interacts with other domains of international law can have significant impacts on its effectiveness. Connections can be complementary and supportive of objectives and functions; they can also create duplication, complexity and conflict. From its roots in early development of international humanitarian law and connections to other arms control regimes, the BWC’s links to other domains of international law have proliferated over time, and understanding this context can aid assessment of its present status and likely future course. Some of the connections are more obvious, particularly with increased awareness of the breadth of biological threats facing humanity—and the last decade has seen strengthened awareness of and collaboration with international organisations responsible for protecting human, animal and plant health. Other connections are less well known—for example how the BWC interacts with the Convention on Biological Diversity and its Protocols—and have the potential for introducing unexpected shocks into global systems for addressing biological risks, such as the crisis over the sharing of viral genetic resources in 2007—an issue which is currently impacting negotiation of the new pandemic treaty. This chapter will trace some of the key areas of intersection and connectivity between several domains of international law and the BWC over the last fifty years and outline some of the opportunities and challenges they present as the way forward for the Convention is navigated.