Prisoner Radio is generally described as radio and audio content that involves prisoners and their communities, either produced outside of prisons to broadcast to a general public, or inside correctional facilities, targeting and limited to a prison-based population. This chapter highlights the difficulties in categorizing this complex media genre. The authors employ a collective case study approach – from Australia, Poland and the United Kingdom – to explore key themes that impact upon the development of prisoner radio internationally. It is argued that a combination of geographical and political contexts, alongside human dynamics and technical requirements, determine how prisoner radio evolves in each specific context. The parameters of prisoner radio must be more clearly understood if it is to be relevant, successful and sustainable.