Recently, foreign direct investment in land, also termed 'land grabbing', has increased significantly in developing countries. In response to growing concerns about its detrimental impacts, the UN Food and Agriculture Organization (FAO), the World Bank and other multilateral organizations have come forward with two proposals, namely the Voluntary Guidelines on the Responsible Governance of Tenure of Land, Fisheries and Forests in the Context of National Food Security (FAO 2012, FAO guidelines), to protect people's rights, and the Principles for Responsible Agricultural Investment that Respects Rights, Livelihoods and Resources (FAO et al. 2010, RAI principles), to make such investments more responsible. One of their central tenets is that investors and host governments respect local people's existing property rights over land by formalising them in a transparent and participatory manner. The article challenges the two proposals -and thus much of the recent land grab debate -from a legal pluralism perspective, by showing that they do not adequately consider the existence of plural legal orders over land and the dynamics of power and everyday practices inherent in property relations. Referring to empirical evidence from Tanzania, Nepal, and Kyrgyzstan, we raise three fundamental concerns about the formalization of property rights. First, we demonstrate that the recognition of customary rights is a very complex and delicate endeavour, which risks neglecting existing property claims and rights. Neither of the proposals addresses this in a satisfactory way. Second, we understand that formalization by state intervention is sometimes necessary, but in those circumstances we cannot recommend the centralist approach of formalizing property rights, as proposed in the RAI principles. In many contexts, this approach has resulted in adverse effects for local communities rather than strengthening their rights. Third, a more rights-based vision as brought forward by the FAO guidelines still bears the risk of reinforcing unequal local power structures. Yet, this vision leaves it to local communities to decide whether their land should become a marketable good to outsiders or not. However, the introduction of such a property regime requires fundamental changes in governance. This cannot be addressed adequately within the framework of guidelines alone. Instead, more long-term strategies for the protection of customary rights are required. Thus, from an analytical perspective, a moratorium on 'land grabs' would be most appropriate. From a more pragmatic perspective though, we acknowledge the FAO guidelines and -to a much lesser extent -the RAI principles as more immediate efforts to reduce negative effects of 'land grabs'. However, investors and host governments should not mistake these guidelines as guarantors of ostensibly harmless land acquisitions. Finally, this article concludes that employing a legal pluralism perspective is very helpful in gaining a more holistic understanding of potential effects and proposed me...