As universal testing moves onto the HIV agenda, there is a need for more understanding of the relatively low uptake of HIV testing and the dynamics of disclosure in Sub-Saharan Africa. Despite the expanding provision of anti-retroviral therapy in Zambia since 2004, disclosure of HIV status - beyond a closed network - remains limited. Drawing on 20 years of living and working in a high HIV prevalence country, research on HIV-related stigma and existing literature on disclosure, this paper explores the reasons that lie behind limited disclosure. Unravelling why HIV disclosure remains "a navigation in a moral field", the pattern of silence around HIV and the routine and often subtle presence of HIV in daily life reveals two key dynamics. The first dynamic is shifting public/private boundaries and retaining a wider identity. People living with HIV juggle the pragmatic advantages of disclosing to a limited circle with the importance of maintaining not only their moral integrity, status and (for some) professional and group identity but also of maintaining their privacy. A more public disclosure ("speaking it" more widely) shifts private-public boundaries and can be threatening, dangerous and can fix identity. Furthermore, disclosure carries obligations which, given high levels of poverty, can be hard to meet. The second dynamic is a pattern of implicit understanding. It can be easier in a context of high HIV prevalence to opt for silence, in its various forms, with the presence of HIV implicitly understood but not often explicitly spoken about. Although this gives more room for manoeuvre and for respect, silence too can be dangerous and certain situations dictate that it is better to breach the silence. More aggressive promotion of HIV testing needs to both respect and consider how to work within these existing dynamics to facilitate safe disclosure.