This article takes a critical look at the development of international humanitarian law (IHL), from its early codification in the Hague and Geneva Conventions to the present day. It examines why and how IHL develops – through treaty, custom, interpretation and soft-law instruments, as well as the influence of jurisprudence and other branches of law. In doing so, it highlights some of the distinctive elements of IHL that set it apart from other bodies of law and explains how these elements influence IHL development. Turning to the present, it addresses some of the key arguments commonly heard against attempting any further development of IHL, by answering the following three key questions: Does IHL need to develop further? If so, how can this be achieved? And what are the prospects for such development in the near future? In answering these questions, the article argues that IHL will continue to develop in many ways, and that while the current environment does not appear propitious for new legally binding norms of IHL, they continue to be both necessary and possible.