This article uses an analysis of the securitization of HIV/AIDS as a basis for proposing three contributions to securitization theory. Beginning with an examination of some of the key debates which have taken place between the Copenhagen School and its critics, the article goes on to argue that the process of securitizing HIV/AIDS was in fact significantly more complex than has been generally recognized and, crucially, that a more nuanced reading of this case highlights a number of issues that are not well captured by the existing securitization theory literature. The first is that securitization can be a multi-level process, with distinct securitizing actors and audiences at each level. The second is that securitization can best be understood as a continuum rather than a binary condition, and that different members of an audience may place an issue at varying points along this spectrum. The third contribution we seek to make is an intervention in the debate over the role of empirical evidence in securitization, suggesting that claims about 'empirical reality' form a crucial part of securitizing speech acts, but that where doubts subsequently arise over the evidence for this 'reality', securitization can be undermined, a dynamic that we show in practice in the HIV/AIDS case.