This chapter examines the underexplored issue of when the constitutional protection for property rights is engaged, thereby highlighting a significant threshold issue in constitutional property law. This raises complex, contested questions concerning the meaning of ownership, including whether it should be understood in interpersonal terms or in terms of individual relationships with 'things', and whether it involves a 'bundle of rights' that can be packaged in various ways or entails core or essential powes for owners. It shows that the legal impact of these ideas is more complex and involves significantly moe overlap between competing perspectives than their dichotomous presentation at the level of theory suggests. FInally, it analyses the political effects of a wide-reaching interpretation of constitutional property rights guarantees, assessing the progressive property concern about the potential for constitutionalisation to entrench the status quo. The Irish experience shows that constitutional property rights can have political effects that are not always aligned to, or reflective of, their strict legal effects.