Since the early 2000s, legal development cooperation has displayed an increasing willingness to engage with customary justice systems. However, this engagement is frequently problematic. External actors often lack knowledge about the different versions of customary law, the negotiable nature of customary justice and the power differentials involved in defining customary law. In customary justice systems, norms are defined and negotiated in administrative structures and dispute-settlement institutions. Inclusion in these fora is therefore of paramount importance to improve the position of vulnerable groups. To illustrate the point, this article analyses two case studies of customary justice reform, respectively focusing on gender dimensions in northern Namibia and land management in Ghana. These case studies demonstrate that when programming ignores issues of power and empowerment, it will not have the hoped-for positive impact on vulnerable groups.