The practice of long-term immigration detention is a relatively recent aspect of Australian Government policy. There has been much debate about the wisdom of such policy, raising concerns regarding the health of detainees, the dereliction of human rights, and the legal robustness of such practice. Despite considerable interest, little detail is available describing who is being held and the reasons for their long-term detention. This paper addresses this noticeable gap through a systematic analysis of the Commonwealth Ombudsman's Immigration Reports over the period 2005 through 2009. From such reporting it has been possible to produce a demographic profile of people held in Australian detention and to develop a taxonomy of the reasons contributing to the ongoing containment.